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GridPro GUI Manual

1. amp Surface I Topology Grid L Property O A Od bef P D Vv Bai v os Z Corner Groups New Save Delete Frame Snap Pick All Current Wireframe Surface Ggrid Validity Glob al dock S Selection mma RA bd Ff B Se Hee SEE Load Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Start Stop noo 2s i229 bee eal Set Toggle display Fit 1 section F Workplane f g toolbar 4 Workplane H Fit 3 Ds i Right side ee f panel a p ja Center of rotation s iai Global axis H Handle Drawing area Surface toggling Grid information Num Blocks 0 za 1 Num Cells 0 li surtace lt zIhi ere iaie Help Figure 2 1 GridPro GUI The empty space in GUI is referred as drawing area which displays all the surfaces topology and grids depending upon the tab you are working on You perform actions using the tools available in the GUI At the top of GUI menu bar is located that has five menu s 1 e File View Help Surface Tools and Solver Then below the menu bar global dock is located The global dock gives access to all the tools that are common to all the tabs Frequently used tools are also added to this dock for convenience In addition to this toggle display section is also located in global dock All the tools related to each tab are located in right side panel of each tab All tools are categorized based upon their use Below the tools section there is popups section where
2. 0 0 0 0 0 0 Ok Cancel Apply Figure 4 16 Specify tab dialog box When you move the cursor to the corner the cursor changes to corner selection mode circular ring right click on mouse which will show the options as in figure 4 17 The corner info option displays all the information about the corner such as corner 1d corner location corners which are linked with it surfaces to which it is assigned and the corners paired with it in case of periodic surface as shown in figure 4 18 Corner id Coordinates Linked Corners Surface Assigns Paired Corner Corner info Set coordinates wW Center of rotation Figure 4 17 Right click menu of corner 11 645714 0 000000 10 879074 Corner id Coordinates 32 11 645714 0 000000 12 930314 28 26 828400 0 000000 26 061760 11 645714 250 000000 10 879074 18 974858 0 000000 10 879074 Surface id type 0 tria pipe tria plane Built in Figure 4 18 Corner info dialog box The set coordinate option allows you to redefine the corner position with specific coordinates that opens a dialog box where you can enter the coordinates for the corner to position Figure 4 19 shows the dialog box of the set coordinate option Coordinates 11 645714 0 000000 10 879074 Message Three floating point numbers separated by whitespace Figure 4 19 Set coordinate dialog box The center of rotation option fixes the center of the rotation of
3. Sees Soe 33 RAEN Mente SR NNESEUELLILORE a ri ATS ie HTT H HTA gt TA PO eases Sa TL Figure 6 12 Block skeleton Switch to the 2D properties tab in property section after selecting the desired solver format in solver menu Remember in 2D properties tab a property can be assigned to each face of each grid sheet even 1f the faces intersect Select the property to be assigned in the property field The four buttons in the selection row the new ii toggle LJ add Bi subtract mn buttons helps in assigning the current property to faces This row has operations relevant to the activation and display of the skeleton of faces If the face is hidden the center of the face skeleton will be deactivated Conversely if the face skeleton center has to be activated the face has to be displayed first If the desired property is not in the list of 2D properties tab click on new C button in the selection menu after selecting the desired property name to add it to the property list The newly added property becomes the current property Assigning the current property to a face involves the center of that face s skeleton 180 Depressing the button will display the skeletons of the faces which do not contain the current property and allows the user to assign the current property to any one face by clicking with the left mouse button on the center of the face s skeleton Depressing the Lt button wi
4. 4 All sheets surface 1 x surface 2 U aie current by clicking on it The checkbox can be used to surface 4 E show or hide the respective sheets Using the delete icon surface 5 x next to the grid sheet name the respective grid sheet can i x be deleted surface 7 The first two buttons i e forward step and backward step below the grid sheet list allows to scroll the current sheet through all the positions within that 7 na mig e eee acc a0 block Forward button steps the sheet forward while backward button steps backward It is useful when a sheet is created using slice button and the user want to check how the current grid sheet is moving across that block The rest of the three buttons function similar to grids Third button i e show all grid sheets E will turn the display on for all the grid sheets 4 All blocks in the above list for the current grid The fourth button gcheck hexgrd x i e show only current sheet will hide all other sheets in the list for current grid and will show only current sheet of current grid The fifth button toggle all grid Sheets will flip the visibility of all the grid sheets The Blocks tab displays the grids that is loaded into the GUI As discussed before the blocks tab works similar to the Grids tab but the only difference is in the Figure 5 25 Blocks tab 168 grids tab every operation is performed on both blocks and sheets of a grid whereas in the Blocks tab i
5. T eo depress the button first button located in Trim panel and click on whatever centers have to be activated or deactivated The button is an addition operation which when depressed it allows the user to create a purple box with the right mouse button and enclose the box around all the centers that has to be activated The button complements the l button When depressed the E button allows the user to create a purple box with the right mouse button and enclose the box around all centers that has to be deactivated The Ei button is an intersection operation Similar to the a and iF operations the i operation allows the user to create a purple box and enclose it around centers Any center which are not enclosed by this box will be deactivated Activated centers enclosed by this box remain activated and deactivated centers enclosed by this box remain deactivated The fy button when depressed simply activates all the centers The Z button when pressed activates all the deactivated centers and deactivates all the active centers 171 Grid isch ath skeleton Trimmed grid blocks with skeleton Grid sheet Grid eeo ckeleron Trimmed orid sheet with skeleton Figure 5 29 Grid trimming 5 7 2 Sheets Like blocks Sheets can also be activated and deactivated Also like blocks grid sheets can be activated and deactivated using the available buttons as shown in figure 5 30 When the trim mode is set to Sheets all the trimmi
6. 4 Property sheets PDC Wall PDC Interblk PDC Outlet Tile View Help Surface Tools Solver T Property aR tA er ae e amp g Save Delete Frame Snap Pick All Current Wireframe Surface Ggrid Validity A ARA b 9 es Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Start Stop ped File Current property sheet View Help Surface Tools Solver Frame OF Zoom gi stoee a 0 Tf Cians ee Num Blocks 12 Num Cells 47616 Figure 6 4 2D properties section with Inlet as current property Property aig Q ww Snap Pick All Current yD Unzoom Probe Select Display He eg Wireframe Surface Ggrid Validity J e 6 Workplane Grid Stat Stop Inlet Property saeco ll ci noana a EY aS eee ara n EENAA sali surtace id 0 fib tag Topology State Help Num Blocks 12 Num Cells 47616 Figure 6 5 Property sheets switched off in 2D properties section 177 First button located at the bottom of the Properties section i e show all property E button will switch on the visibility of all properties sheets blocks in the list respective to the tab Fie View Help Surface Tools Solver 1 Property D gt oe Tr W Vv Ba v 2D Properties Frame Snap Pick All Current Wireframe Surface Apopa a QA Q gt Ww g amp See Zoom Unzoom Probe Select Display Workplane Grid Num cat
7. Figure 4 61 shows the corners merged at different positions HA EE BREE Two disjoint wireframes Merged to center Merged to Selection 1 Merged to Selection 2 Figure 4 61 Corners merged to different positions The other way to merge is by using Groups Switch to Group tab under Merge dialog box as shown in figure 4 62 Firstly place the two sheets of corners into two different corner groups Then select the two respective corners groups Then decide at which position you want to place the merged corners If you want to merge it to center of the two selected corner sheets enable to center If to center is not enabled it will position the merged corners on the second selected group 113 _ To center Select group to Select group Ok Cancel Apply Figure 4 62 Group tab dialog box 4 4 2 Move The corners need not be positioned precisely in GridPro to obtain a grid But positioning it reasonably reduces the grid generation time So more often you would like to move the corners in order to position it reasonably especially when you try to converge the grid generation process You can translate a corner by moving the cursor to the corner and dragging the corner by using the left mouse button Figure 4 63 shows the dialog box of the move nee button Move on tab appears by default that allows you to move corner parallel to workplane A corner can be moved along and normal to workplane and current surface The flags
8. iF deletes an arbitrary part of a whole path To perform the deletion depress the remove path E button and drag a box on the part of the path to be deleted using the left mouse click To select the specific part of the path depress the retain path i button and drag a box on that part of the path using left click Notice that the remove path T and retain path EI buttons remain depressed until it is re clicked The delete path x button when clicked deletes all the paths The undo path Operation acts as a partial one step undo The operation will delete the path that was just created but not re create the path or part of path that was deleted 12 Once a closed curve is formed or a part of a surface cell is selected it can be segmented using the Segment button If the curve is not a closed one the splitting operation will fail In other words the endpoints of the curve must intersect or lie on the border of the surface which can be checked by depressing border BE button Also if two disconnected curves are created the Split operation would fail An error message as shown in figure 3 26 pops out when the split operation fails Figure 3 27 illustrates examples of segmented surfaces If Split succeeds a message in the status bar will read surf has 2 pieces and one such piece will become a different color while one remains sea blue You can continue segmenting pieces as much as desired Like surfaces and sheets pieces are ei
9. Frefix curve_ number of refinements is zero the output curve is just a copy of the corners provided Two different schemes are provided for generation of these curves which can Apply Cancel be selected from the drop down provided next to methods If the Interpolating scheme is used the Figure 4 114 Controlnet Curves dialog box final curve passes through all the input corners of the topology The Approximating scheme results in curve which may not pass through the input corners The input corners are used mainly to guide the curve Note that the curve will always pass through the end points irrespective of the scheme used The corners in the input corner group are automatically assigned to the output curve The name of the output curve can be provided in the prefix field When there is branching three different edges emerging from a given corner it is not possible to output a single linear surface and hence the input corner group is split into different non branching groups and a curve is generated for each of these non 148 branching groups All the curves generated using the above mentioned parameters the number of refinements and scheme All these curves are saved as prefixl lin prefix2 lin based upon the prefix you give Figure 4 115 shows the branching input controlnet and output curve Figure 4 115 Branching wireframe and its corresponding controlnet curves 4 10 7 Tube A tube surface can be defined by the
10. Group c3 with G mode Group c3 with R 1 mode Figure 4 54 Different grouping modes 4 3 3 Surface Assignment Group The button is a special group However this group always contains the corners assigned to the current surface and is thus named the surface assignment group Therefore you can change the contents of the group just by changing the current surface Often when surfaces are close together the corners assigned to each surface appear to be right on top of one another Using the button will allow you to pick out the corners assigned to one of those surfaces and allow you to manipulate just the wireframe about that surface Like any other grouping operation you can use the corners in the group to add subtract to from any group but corners cannot be added subtracted to from this group like any other group 109 Figure 4 55 S group topology 4 3 4 Group Retrieve Option Similar to undo or redo options for topology building the corner grouping actions within a group can be retraced If you have added corners to a group using more than one red box adding corners to a group at different times you can retrace your previous steps by pressing the cl and lb buttons found next to surface assignment group Practically speaking these buttons are very useful By enabling you to visit previous selection in a group these buttons allow direct access on the parts of a group that were the results of your actions e g wrap copy
11. If Ggrid is running a confirmation dialog is popped up as shown in the figure 2 63 If Ggrid is running on a disjoint topology 1 e if there are multiple Ggrid processes running simultaneously they are all killed after confirmation But if the grid generation engine is not running an error message 1s displayed see Figure 2 64 Are you sure you want to stop Ggrid no live ggrid to kill Figure 2 63 Confirmation dialog box Figure 2 64 Error message when ggrid is not running 4 2 3 21 Gerid Start euler Restart Restart euler Gridden Schedule Figure 2 65 Ggrid drop down list e Restart Once GGrid is stopped and after looking at the grid you realised that it would have been better to run it for few more sweeps to get a good quality grid you can use Restart option y under Ggrid button to resume the previous computation The last saved dump file is used to restart the grid generation engine If an instance of Ggrid is already running an error message is popped up as shown in the figure 2 54 and if the topology is invalid an error message is displayed as shown in figure 2 53 If the topology is valid a file dialog box as shown in the figure 2 66 is displayed to select the appropriate dump file having tmp or grd extension Input dump name Ok Cancel Figure 2 66 Restart Ggrid dialog box Note that here it is assumed that a previous topology is modified and Ggrid is restarted Hence a scheduler is not launc
12. In order to continue building the wireframe after nesting you need to group the outermost layer in a group and start working on it You can group the outermost layer by selecting a group number from the outer group drop down list Ensure the group that you provide in the outer group is an empty group The length group is the corner group where the length between each nesting layer will not be changed due to smoothing The number of smoothings is the number of times the smoothing algorithm has to be run on the resulted ribbon nest layer You can also add a wrap layer after creating the ribbon nest by enabling should add wrap layer check box This helps to avoid skewed cells created in the surface because once the ribbon nest is created the outer layer will have corners shared by 4 edges If you start creating a wireframe from that corner it becomes a corner shared by 5 edges In order to get a smooth transition on the surface it s better to add a wrap layer after creating the ribbon nest 4 10 5 Controlnet Surface In GridPro the quad surfaces are generated using the Controlnet Surface tool In order to create a controlnet surface click on the Controlnet Surface button in the drop down list of the Surface Tools menu in the menu bar Figure 4 113 shows the controlnet Input group Select group surface dialog box Controlnet surfaces are created Feature group Select group based upon group of topology corners you input Select Smooth group S
13. Once the option is selected you will be prompted with the message for confirmation of the execution of the command as shown in the figure 4 73 Do you want to create complete topology from periodic Figure 4 73 Confirmation dialog box 4 5 2 Mirror Mirror tool Miter is helpful when you work on a symmetrical geometry It can also be used when the part of the geometry is symmetrical To mirror an object a plane of symmetry and the normal of symmetry is required Figure 4 74 shows the Mirror Topology dialog box Similar to rotate mirror 1s also having some predefined options apart from the user defined Selecting the user defined option gives the control to define the plane of symmetry and the normal of symmetry A point on the symmetry plane needs to be entered in the center field which will calculate the plane of symmetry while the normal of symmetry need to be given in the normal field Selecting the workplane options mirrors the corner and surface group with respect to the 121 workplane It assumes the workplane position as the plane of symmetry and the z axis of the work pane as f ory normal of the symmetry The pre defined three options _ B mirrors the corner and surface group with respect to the hapan ee global plane i e XY YZ and XZ plane The normal for XZplane Workplane these planes are assumed implicitly using the options User defined itself 1 e XY plane defines that the normal is on XY Create a c
14. a dialog box will open in the right side panel as shown in figure 5 18 Specify the direction along the side the copy has to be created If X or Y or Z is selected it will create only one reflective copy along that direction merged with original grid with an addition of tmp as an extension to the original output file name Newly merged reflected grid will also be loaded into GUI in addition to original If periodic is selected it will create the copies based upon its periodicity and merge all the copies into a single grid file name with tmp as an added extension to the original grid file name The new grid file will be loaded into UI in addition to previous grid file There will be two grids existing in the UI original grid and a newly created merged grid Suppose 1f a wrong axis is selected undo the process by clicking on the Undo button and redo the process by selecting the correct axis Extension X Undo Cancel Apply Figure 5 18 Mirror dialog box 163 5 4 Grid Probing Utility 5 4 1 Spacing Sometimes user will need to test the smoothness of a grid or to measure precise dimensions of a grid The distance between two nodes can be measured precisely by first pressing the spacing button g found in Tools section of the right side panel in the Grid tab then moving your cursor to the line connecting two nodes and by clicking the left mouse button Color display mode must be in the color by sheet mode in order to use spacing b
15. il 12 22 43 50 51 55 56 66 67 69 83 84 89 106 112 119 123 128 133 4 9 4 10 4 11 Surface Assignment Utilities Surface Building Utilities Gridding Process Chapter 5 Grid 5 1 2 5 3 5 4 5 5 5 6 5 7 Grid Viewing Utilities Preprocessing Utilities Post Processing Utilities Grid Probing Utilities Quality Check Parameters Grid Toggling Section Grid Trimming Utilities Chapter 6 Properties 6 1 6 2 Properties Section Solver Section il 140 144 151 155 156 160 161 164 165 166 169 174 175 179 CHAPTER 1 INTRODUCTION A good general purpose grid mesh generator should be at least good on two accounts 1 Quick and easy to setup typical complex gridding problems The considerations include the first gridding turn around time the subsequent parametric design turnaround time the modular parametric design adding and subtracting features turnaround time and the clustering capabilities for CFD use 2 Good grid quality such as the grid smoothness orthogonality desired grid distribution and surface fidelity Both accounts are better served through automation with different levels of user selectable controls For a multi block structured grid generator automation can be classified into four areas 1 Surface restructuring amp repair 2 Topology generation 3 Book keeping of topological information 4 Optimum distribution of high quality grid To t
16. in 3 d a regular one has 4 neighboring blocks An internal edge having three neighboring blocks is called a singularity of degree 3 Similarly an internal edge having five neighboring blocks is called a singularity of degree 5 It is more difficult to generate good grids around a singularity as the degree moves farther from the regular number 4 GridPro restricts the degree of a singularity to be either 3 or 5 to 7 However one should almost exclusively limit his singularities to degree 3 and degree 5 A singularity of degree higher than 5 can always be split into several singularities of degree 5 using a general procedure without completely redesigning the topology The tradeoff is increasing the number of blocks A simpler procedure will work most of the time For a 2 d case Figure 4 87 is a local view showing how a singularity of degree 6 can be split into two singularities of degree 5 128 B Figure 4 87 6 degree singularity split into two 5 degree Singularities of degree higher than 5 are used for the cases where their use will significantly reduce the number of blocks When a sufficiently high degree of symmetry is present in the surface geometry and in the block topology near these singularities the blocks around a singularity will be more or less uniformly distributed So you should avoid putting singularities on surfaces In other words you should try your best to design a topology that wraps around the surfaces The f
17. parallel perpendicular workplane and current surface allow you to move the corner either parallel or perpendicular to the workplane or current surface Switch the tab from Move on to Translate It gives control to translate the active corner and or surface group to a given location Enter the coordinates in the given fields to translate the corners and surfaces This is helpful when you know the location of the translation Translate current group by Direction X axis Y axis Z axis oo 86 oo J OO Workplane Surface Parallel Normal Ok Cancel Apply Figure 4 63 Move to dialog box Figure 4 64 Move to dialog box Sometimes you may want to move a group along with the workplane In order to move a corner group first fit the workplane center to the center of the active corner group using the Fit buttons in the left side tool bar and then switch on the handles of the workplane by clicking on 114 the Handles button in the left side tool bar Then switch on the move button and move the workplane to the desired location where the grouped corners have to be moved You can also shrink the corner group size i e the edges connecting the corners will get shrunk by shrinking the workplane size using the workplane nodes Note that the move button is not automatically undepressed after being used 4 4 3 Copy For geometries with same cross section or symmetric sections it is easy to build the wireframe in 2D and extrude it to 3D In order
18. 41 Surface information d Hide option hides the selected surface To know how to unhide show the surface refer section 2 5 Delete option deletes the selected surface that can be restored by clicking on the UNDO button in topology panel Orientation option is used for changing the surface orientation Transform button can be used to translate rotate scale and mirror the surfaces which is explained in section 3 4 7 Display type shows the list of display types available in GridPro using which the surface display of selected surface can be changed Refer section 2 3 14 for more information 82 CHAPTER 4 TOPOLOGY In order to grid regions it must be covered with wireframe topologies that crudely follow their boundaries The majority of GridPro operations deal with creating and modifying topology Remember a topology consists of a wireframe and surface assignments GridPro is a unique multiblock grid generation program because it revolutionizes how volumes are gridded Usually multiblock grid generation programs require users to assign topological attributes separate parts of a topological framework laboriously to individual blocks whereas GridPro automatically assigns separate parts of a topological framework to individual blocks Remarkably GridPro can also grid loosely positioned topology In other words GridPro will grid topology whose position only roughly conforms to the corresponding geometry A wirefram
19. 60 Disjoint topology Ggrid dialog box Once the prefix and sweep interval are given as input the confirmation dialog as shown in the figure 2 61 is displayed The disjoint topologies and their corresponding schedule files are written You can modify the schedule files if necessary Continue Figure 2 61 Confirmation dialog box The user can modify the schedule files at this point if necessary and the user can continue by clicking on the ok push button The Ggrid processes are run in parallel and the output of each of these processes are redirected to their own output windows All these windows are added to the output panel Figure 2 62 shows multiple windows in the output panel 40 lt r File View Help Surface Tools Solver a I Topology i Prop Pa Lae a lt i DP aR BA OV Ree n New Save Delete Frame Snap Pick All Current Wireframe Surface Ggrid Validity mana agagagagegronaoaswss Load Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Start be Set Stop iS Fit 1 Fit 2 Fit 3 rt BE 00a B k a Fix DEEKIE L l aed surtaceid 2 ziii Figure 2 62 Multiple output tabs Tag Topology State v Help These windows will be closed automatically once the gridding process is stopped 2 3 20 Stop Gegrid You have to stop the Ggrid engine manually once started To stop the Ggrid click on Stop ss Ggrid icon P located in global dock
20. ANA PARAAN ERNA RAR TARAANINNA Figure 5 4 Grid block with face sheet and slice sheets CC E a PE eo ptt tL HHHH Eem Ba A T ETHE have distinct faces and distinct slices Many linked faces ae Tn A 2 HEH me ts To view the overall grid or mesh click on Mesh g button located in the Tools section in the right side panel All grid points which are displayed when the Mesh button is depressed Figure 5 3 Grid blocks with a sliced sheet Let us summarize Distinct blocks sections to observe specific features such as the density of the mesh lines or the number of or many linked slices comprise a sheet either a face sheet or a slice sheet A face sheet can be either a shell or a partial shell Manipulating blocks faces slices and sheets will help you to look inside and analyze parts of grids For complex grids you will want to check numerous cross define miniblocks or cells Corners are to blocks as grid points are to cells O Sb D aaa a ENT l semana IVA 2 F 3 2 N ae 3 a ON N Figure 5 5 Grid blocks with mesh 157 5 1 2 Faces Faces button is used to create sheet consist of all block faces on all the external grid surfaces It create grid sheets for all surfaces displayed in a different colors Clicking on the Faces button opens Display Faces dialog box as shown in figure 5 6 To create grid sheets on external surface boundary surfaces use
21. Boundary button similarly for internal surfaces use Internal button By default the Boundary button is depressed Se sis See 6S Se e r Le ee CL HTH CL HHH HHHH HHH HHH mAH CLL AL LEUARAATA AAY EEEH EEH HH an a ma eo ee ince MTT fi See eT My ees a He AEE is ae sear ae iy PTET Eee is oF AoE rte ane ow HEH EH TTT Internal Boundary PCE EEE HEEE HHHH Cancel PEE Et EH EEE HEHEHEH BEPC tp EEC Figure 5 6 Faces dialog box Figure 5 7 Grid blocks with boundary grid sheets 5 1 3 Slice Aside from creating sheets about surfaces you can also create sheets at any desired IJK setting By pressing the Slice button then clicking any point on an edge you can create a sheet composed of slices The sheet will appear probably close to where you click on the edge at the closest IJK constant index After creating a sheet you can use the buttons operation in the grid Sheets section in right hand side to step forward or backward a sheet The stepping process of the grid sheets is explained in the section 5 6 e Right click menu Block edge 4 2916 info When you right click on an edge of a grid block a menu Center of rotation appears as shown in figure 5 8 First option shows the grid block 8 Add grid sheet edge information It will show block index no edge index Change density number along with the edge density You can pick particular Figure 5 8
22. a group can do you should first learn how to access a group Amaximum of nine groups can exist for any topological components in a single topology file Each group is numbered one through nine with c as prefix for corner groups and s as prefix for surface groups Groups are located below toggle display section in right side panel Groups are divided into two tabs such as Corner Groups tab and Surface Groups tab Corner groups tab can be seen in figure 4 52 When you depress one of these buttons the number on that button activates that group number Therefore when the c6 button is depressed group c6 is active Only one group can be active at a time Corners can only be added to or removed from Figure 4 52 Corner Groups tab the active groups Initially no corners exist in any group Groups can be thought as empty containers Therefore at first you can only add corners to groups After depressing a one through nine group number you may add corners to that button 1 e second icon in selection section in corner groups tab This gel operation allows you to drag a red box with the right mouse button about corners The corners within this box will be added to the group number depressed Just as the button lets you subtract corners from groups This 2 button requires you to drag a red box around corners Of course you can only E a take corners out of groups to which you have already adde
23. are the alphabets A to Z without any modifier keys like Ctrl Shift or Alt The modifications will work across the sessions except for the background color to retrieve the default settings click the Default button in the popup window as shown in the figure 2 12 Usage Delete corners edqges Link corners Insert layer Append corner Probe object Face exclusion Surface assignment Add Corners to Group Adjacent layer Edge creation Merge corners Pick COR Object info Auto save frequency in minutes 2 Font size in pt E Background color Select Default Ctl D Save settings Figure 2 12 Default keyboard Shortcuts Font size can be changed by defining the desired value in the field next to font size It will change the size of the font displayed in the UI 14 Background color can be changed by clicking on the push button Select colour which opens a dialog box as shown in figure 2 13 The RGB value of the desired color has to be given in the respective fields In addition to that few standard colors can be chosen from the Sample colors drop down list GUI saves the topology automatically with _auto fra name based upon Auto Save Frequency By default Auto Save Frequency is 2 hence GUI will save wa the topology every 2 minutes with name _auto fra This Sample colors default Me is to ensure that even if the application crash Cancel unexpectedly the topology data is not lost You can modify the
24. create surface passing approximately through all the input corners it may not be passing through all the input corners In interpolating method it tries to ensure that controlnet surface is passing through all the input corners Sphere like method is similar to interpolation where surfaces passes through all the corners but between the two adjacent corners it tries to create a sphere like shape The surface will always pass through the end corners irrespective of the method used The output file can be named by clicking on the push button next to the Output and mentioning the desired file name The extension for this file should be guad You can change the location of output file if desired Click on Apply after defining the output file name to create a control net surface 4 10 6 Controlnet Curves To create a curve click on the Controlnet Curves option in drop down list of Surface Tools menu in the menu bar Figure 4 114 shows the controlnet curves dialog box Similar to controlnet surfaces the controlnet curves are created based upon the input topology corner group Select the corner group next to the corner group field for which you want to create curves The number of levels of refinements can be defined in the Refinements field The greater the number of Corner group Select group refinements the greater the number of points in Refinements 3 the output curve and hence smoother the curve If Method Interpolating
25. does not completely converge Still the resulting grid quality is far better than what you would expect from traditional methods Sometimes if the gridding process is stopped too quickly it will produce a grid whose coordinate sheets fold in on themselves at some location or locations Therefore you must allow GridPro to sort out all surfaces In the status window a stream of consecutive sweep messages are periodically interrupted by the reading fold count When the number following fold count reaches zero all surfaces have been sorted out The fold count gives the user a coarse means to judge the convergence of the process Generally in the convergence non zero fold counts appear only in the early stages well before it 1s worthwhile to inspect the residual the residual becomes the main focus of your monitoring once you are at zero folds Your attention is then redirected to seeing when the residual settles down to a constant value While the grid is converging you have the option to take the grid for use at that intermediate stage or wait until a more full convergence of the optimizer has taken place 152 gt Scheduling at step 1ifswp 6 with 3 actions taction g all 1 000000x mark nt 1 mark e eid den ent a oad 4 1 oad 4 total points needed points 192x96 500x8 6 MB allocated b i points 192x96 500x8 6 MB no change taction 3 166 new sweep interval 108 sup A O8 646 8 max r6 139 c 606 680 57 76e 62
26. enable you to perform a variety of basic and complex procedures without having to manually write TIL Topology Input Language code with its associated minutiae and rules Benefit of TIL code on the other hand is the versatility of being able to handle all possible scenarios The topology codes are written to TIL code files These files can be created by either interactive means or manual text edit and can be reused edited or combined Being the only program boasting a fully compiled language GridPro provides you with the option of working in the TIL code or the GUI The GUI provides an interactive environment for the gridding process an environment that allows the user to see and manipulate the object being gridded Also the GUI is the underlying system that enables GridPro to transform topologies into grids The resulting grids are structured multi block grids In this manual the effective usage of the GUI is thoroughly presented 2 1 Introduction to GUI The GUI window is designed in such a way to guide through the grid generation process required in GridPro to get a good quality grid The main window consists of four different tabs such as Surface Topology Grid and Properties which helps the user to work on different tabs simultaneously Each tab has a drawing area top menu bar global dock workplane toolbar right side panel and a bottom bar File View Help Surface Tools Solver enu Dar
27. file Xpolar doesn t have any representation but in GUI it has been displayed as a Torus shape for convenience The axis extending through the torus center hole is the periodic axis The torus serves solely as a visual aid and in no way represents the physical properties of a surface The torus can be scaled to any size using transformation 60 Apolar Periodicity 60 Axis X axis Periodicity should be a factor of 360 Figure 3 7 Axis drop down menu Ok Cancel Apply Figure 3 6 Periodic Surface Xpolar tab e XYZ A xyz translational periodic surface is used to create a grid with linear periodicity The grid generated within the given period distance can be used to generate an infinite grid across the periodic boundaries A XYZ periodic surface is defined by its periodicity which corresponds to the length of the section and orientation Its center is origin of global system co ordinates which can be transformed using transformation option discussed in later section Figure 3 8 shows the dialog box of xyz periodic surface Similar to Xpolar xyz object also doesn t have a representation but GridPro displays it as a plane in case of 3D and as straight line in case of 2D for convenience The periodicity is on the axis perpendicular to the line plane 7 a X axis Cancel Apply Figure 3 8 Periodic surface XYZ tab NOTE Both xpolar and xyz surfaces are defined in the same way irrespective
28. frequency by defining the desired value inthe Figure 2 13 Background color dialog box field next to Auto Save Frequency in the Settings window of File Menu bar In addition to _auto fra file GUI also saves a file named _auto undo at every auto save frequency interval which contains all the operations executed on the topology in the order This file is saved so that the undo redo operations can be done in the saved topology file in the same order as it 1s done while creating it When the GUI is started first time after installation it prompts you to define Current Working Directory Current working directory is the directory where all the surface files topology files and grid files will be stored by default until you change the location It always opens the Current Working Directory to load the files All the file dialog boxes use this current working directory to load save files This directory is also used by the other functions in the GUI for e g when Ggrid is started the output files are written to the current working directory When starting a new session it is advisable to redefine your working directory as all auto save files _auto fra _az fra _undo stack and grid files will be saved to that folder which can be accessed easily if needed later Hence it 1s very important to reset the working directory You can modify the Current Working Directory from the Working Directory option under the File Menu as shown in the figure 2 8 A file sel
29. ids Checking block orientation box can toggle the block orientations Grid sheets are useful in viewing grid cross section which can be toggled by checking the sheets box In the grid tab the spacing tool which gives the distance between two selected nodes will be highlighted with red line connecting the two selected nodes Checking the Highlight check box under grid branch can toggle this line e WS pla 4 Grid Blocks Grid sheets Block ids _ Block orientation L Highlight Figure 2 82 Grid sub menu e Others Other than surface topology and grid entities that are visible in graphics window are Global axes center of rotation axes Workplane and workplane axes that are classified under Others branch in Toggle display section By default these are visible in both Surface and topology tabs except for the global axes and center of rotation axes that is visible in all tabs The entire workplane can be toggled to avoid screen clutter by unchecking the box of Workplane and the Workplane axes Note that workplane axes can be shown only when the workplane itself is visible The global axes and center of rotation axes can be toggled by checking the Axes check box 53 a Others Workplane _ Workplane axes Axes Figure 2 83 Others sub menu NOTE 1 If the workplane is used to clip the surfaces grid sheets and if it is hidden the clipping would be disabled 2 Toggling off or on any entity is indep
30. is being done High density group Select group Low density group Select group ha Refinement levels 3 Cancel Apply Figure 4 100 Area nest dialog box r r r r pprt B Figure 4 101 Area nest topology e Topology Densifier Topology Densifier is a special case of Area nest Once clicked it opens a dialog box as shown in figure 4 102 The number of refinements and the para percentage of wrap needs to be provided in their respective fields Once the input is provided it takes Refinement levels 3 the assignments of current surface Make sure the Offset Wrap 10 current surface is the surface where the nesting has to Cancel be applied wrap the corners externally or internally The wrap type is determined from the surface orientation 1 e if it is a 1 sided surface an external Figure 4 102 Densifier dialog box wrap is done and if it is 2 sided surface an internal 138 wrap is done Then an insert 1s made in between the wrap and the area nest is applied as explained above For the area nest it assumes the wrapped corners as the high density group and the inserted sheet as low density group and applies the area nest using the number of refinements provided in the dialog box The wrap percentage is used to do the wrap This is more sophisticated tool compare to the forward nest as it is automated the grouping needs to be done for the forward nest area nest e Reverse nest The fo
31. mouse button Right click on an edge where you want to insert and select the Insert Block option from the list This insert option propagates depends on the mode selected in the insert button The other option in right click menu is Insert Sheet which inserts the sheets in such a 96 way it exactly replicates the adjacent sheets whereas the Insert Block option insert the sheets in such a way it avoids the extra link For e g when you do Insert Sheet on a wrapped topology as shown in figure 4 30 an extra link is created because the outer four corners is also considered as separate block hence it added an edge connecting those two edges but the Insert Block option evaluates such cases and avoid creating such links Figure 4 29 shows the list of options in the right click menu of an edge Wrapped topology Insert sheet Insert block Figure 4 30 Difference between Insert sheet and Insert block First option is edge info that displays the information about edge id the corner id and its coordinates of the corner to which the edge is linked to length of the edge and the density of the edge Edge id 9 End Corners 7 0 600000 0 600000 0 000000 6 0 600000 0 600000 0 000000 Length Density Figure 4 31 Edge info dialog box Figure 4 32 Multi insert dialog box Similar to COR in corner right click menu the COR in edge right click menu fixes the COR of the screen to the selected position on the selected edge Multi Insert opt
32. one of the mode from drop down list By default the grouping display mode is A which refers All When A mode is active the corners in the active group and the edges connected between those corners are Figure 4 53 Grouping modes highlighted while all of the surrounding topology is dimmed G group mode 108 refers to Active Group When G group display mode is active the corners in the active group and the edges connected between those corners are highlighted while all of the surrounding topology is hidden R group mode refers to Reference to other selected group When R 1 mode is active the corners in the active group and the edges between those corners are highlighted while all of the topology in group 1 is dimmed and rest all topology entities are hidden Similarly if R 2 mode is active the corners in the active group and the edges between those corners are highlighted while all of the topology in group 2 1s dimmed Same applies to R 3 R 4 R 9 In particularly complex topologies you may have difficulty focusing on one set of corners By setting the group mode to reference group R 1 to R 9 you localize your work eliminate screen clutter and effectively manipulate specific corners Group c1 Group c3 Group c5 Corner Groups Selection foro ss cele alee Group c3 with A mode Corner Groups Corner Groups Selection JA Hae Selection zea Hae BEERS SP afele Pelee lest alale ael aae
33. region s boundary curvature The optimization is of course relative to the constraint of topology choice usually a rather mild constraint Generally you will get smooth nearly orthogonal grids that are appropriately clustered to both concave and convex boundary curvature The resulting grid is so natural you will become accustomed to high quality grids every time you use GridPro With the interactive GUI the entire gridding process is purely visual The Ggrid launch can be started stopped and re launched graphically which is explained in section 2 3 The Ggrid process is tightly coupled with interactive topology generation topology errors are automatically detected and highlighted in red when you try to launch an incorrect TIL 151 code The highlight appears as an overlay on top of the corners and edges with different colors based on the error The error and highlight display points precisely to the problem area that prevents Ggrid from running Concurrently a more technical error message is also displayed in the console window Once you know the location of an error the error and highlight display that helped you find the error will sometimes be in the way of your corrective actions To remove the highlight uncheck error under Topology menu in Toggle display section If the topology is valid a confirmation dialog box pops out When you click ok the Ggrid process will commence However you will not explicitly see the gridding process
34. reload current option can be undone from the Topology tab Current surface is a tria quad surface Please use the Settings button Cancel Figure 3 37 An error message when a non built in surface is tried to reload 3 4 10 Move node GUI allows the user to move a node of a Current surface To move a surface node click on Node button under Check Repair section in Surface tab Move Surface Nodes dialog box opens as shown in figure 3 38 Nodes can be moved w r t to workplane orientation either along the workplane or normal to the workplane By default it can be moved parallel to workplane direction If Along button is highlighted the nodes move parallel to the workplane Click on Normal button in the dialog box to move nodes perpendicular to the workplane Direction Along Normal Undo Redo Kill Save Figure 3 38 Move surface dialog box 80 Similar to topology undo and redo operations node displacement operations can also be revert back using Undo and Redo buttons in Move surface dialog box Clicking on Kill button will delete all the node displacements All the node displacement operations done on a surface can be saved using Save button 3 4 11 Fill GridPro allows the user to merge segmented surfaces pieces as well as fill the holes created by segmentation GridPro fills holes with tria surfaces hence it works only for tria surfaces To fill a hole in a surface or piece select the surface as cur
35. revolution around a center curve The revolution for each point on the center curve is performed in the normal plane of that point with respect to the tangent of the curve Hence a tube surface is represented by a set of points on the curved center line or axis and a variable constant radii at all the cross sections of the tube A tube surface can be created using the topology corners and edges In order to create a tube click on the Tube option in the drop down list of the Surface Tools menu in the menu bar Figure 4 116 shows the dialog box of the tube The axis of the tube surface can be represented in two ways either by a group of corners added to a corner group or by providing an origin and a direction Similarly the radius can also be represented in two ways either by a corner group or by providing a constant radius value Hence a tube can be created by four different input combinations such as group group eroup value orientation group orientation value for axis and radius respectively When you are using group group combination please make sure both the groups are having equal number of corners In group value combination the radius of the tube would be constant as you are providing a value In _ orientation group Value 5 Output Select a file _ Smoothen tube Refinements 2 _ Add caps to the tube Ok Apply Cancel Figure 4 116 Tube dialog box combination if all the corners in the radius group are pla
36. side will appear Since the clipped graphic display pierces objects you can clearly observe 2 dimensional slices of a surface grid A surface with section views is shown in figure 2 77 49 No clipping With positive section view With negative section view Figure 2 77 Different sectional views 2 4 7 Handles Workplane axes and vertices that are used for translating and resizing the workplane can aa be toggled using Handle Handle button in workplane toolbar 2 5 Toggle Surface Section Most of the times user may want to hide multiple surfaces of the topology Though surface groups can be used for this purpose sometimes it 1s easy to toggle the unnecessary surface by scrolling through them Each surface of the topology has a visibility flag which is used to hide show the surface By default all the surfaces are visible These flags are used to filter the visible surfaces and the some tools help you to modify these flags internally and help you for better visualization Note that the surface groups act as the final layer of filters 1 e the surfaces which are not appended to the current surface group or reference group are invisible irrespective of their visibility flags Tools under toggle surface section as shown in figure 2 78 provide a simple way to scroll through all the surfaces of the topology The indices or ids of the surfaces are used to scroll through them The field show current surface id The current surface is defin
37. skeleton To avoid such difficulties you can use set property option in the right click menu to set the boundary conditions of the chosen solver for any grid sheets You need to create a grid sheet in the place where you want to assign a property As discussed in section 2 3 the grid sheets can also be viewed using different display types by selecting the display type from the right click menu The different display types can be seen in figure 2 51 in section 2 3 5 1 4 Reload The load option in global dock opens a window that allows you to find and access the file blk tmp Note you need not stop the gridding process in order to access the grid In fact since the file blk tmp 1s being updated after every 100 sweeps you can reload an updated version of blk tmp by accessing the Reload Ses Clicking on the Reload button will pop out a dialog button in the Tools section box as shown in figure 5 10 If you select Auto option GridPro will automatically perform the Figure 5 10 Reload dialog box reload operation after every 100 sweeps or every time the grid file is written until the Auto button is switched off If you select Manual it allows you to perform the reload option once 159 5 1 5 Color When you have one or more sheets on display you can select a color scheme that will fit your needs You can color each sheet by slices or faces or just color every sheet differently Color button pops out a dialog box contain
38. such as lin quad tria tube This tool is used to transform the surface by scaling translation rotation and mirroring If clicked on this option a transform surface dialog box is popped out in a window as shown in figure 3 32 The order of transformation is similar to the order of the buttons in the dialog box 1 e initial translation scaling rotation final translation are applied in the same order If the mirroring is enabled all the other transformations are disabled and the current surface is mirrored with respect to the given mirror plane Translation 1 MT 000i CO Scale 10 Rotation center oo oo 0 0 Rotation axis 1 0 00 00 Rotation angle 0 Translation 2 00 j 00 00 _ Mirror Plane center oo oo 0 0 Plane normal 00 o 00 Figure 3 32 Surface Transformation dialog box Firstly a surface is translated using the values in translation Then scaling is done on the translated surface with respect to origin Usually scaling is required with respect to the center of the surface Hence the surface should be translated using translation such that its center coincides with the origin Then scaling transformation is applied after translation Surface is then rotated about an axis parallel to rotation axis and passing through rotation center The angle of rotation is provided in the rotation angle field Translation 2 field can be used to apply any surface translation after the rotati
39. surface Corners can be assigned to zero one two or more surfaces If a corner is assigned to each of two intersecting surfaces then the corner will go to the intersection between the two surfaces For example when gridding a rectangle the double assignment to both a horizontal and a vertical side will attract the corner to the vertex of the rectangle formed by the intersection If it were the case of a box in three dimensions then the attraction would be to a box edge A triple assignment however would send the corner to a box vertex 140 Surface 2 cl Assigned to surf 1 and surf 4 c12 Assigned to surf 1 and surf 2 Surface 1 Surface 3 c3 Assigned to surf 2 and surf 3 c4 Assigned to surf 3 and surf 4 Surface 4 c4 cl Figure 4 105 Rectangle topology with double assignment Corner assignment to the surfaces of the topology is an easy and important step for building a valid topology There are many tools available in the GUI to collect the appropriate comers in a separate corner group so that it is easy to assign these corners to the current surface of the topology All those tools for collecting the corners in different corner groups are described in the section 4 3 This section describes how the corners in the current corner group of the topology can be assigned to the current surface Figure 4 106 shows the Assignment section in the right side panel of the topology tab Note that all these operations
40. tabs 1 li tion is sp d Properties sec figure 6 2 amp 6 3 viewe 2D Properties 4 Property sheets POC Wall r z cL gt 2D properties section Figure 6 2 175 In the 2d properties tab assigned property sheets are shown and in the 3D properties tab assigned property blocks are shown It also gives an access to toggle on off a property By default each grid has two 2D properties such as interblock interior and boundary wall and one 3D property i e Fluid independent of solver format 2D Properties 3D Properties 4 Property blocks PDC Fluid aE Figure 6 3 3D properties section Depending on the tab selected user can assign the properties either to the grid sheets or grid blocks If 2D properties tab is selected properties are assigned to grid sheets and in 3D properties tab properties are assigned to grid blocks In the 2D properties tab only grid sheets will be visible and in 3D properties tab only blocks will be visible Similar to toggling between grid sheets in the Grid tab you can toggle between the property sheets The property name which is highlighted with blue shade is the current property displayed as a sea blue color grid sheet in graphics window Any property can be selected as current property by clicking on that property name To hide a property uncheck the box before the property name If the box is checked the property will be visible 176 2D Properties
41. terminal corners Once the corners edges or surfaces are created their indices cannot be changed later 32 Edge id End Corners Length Figure 2 47 Edge information When the surface is selected the surface data is displayed in the dialog box as shown in the figure 2 48 includes it s index the type of the surface can be one of the plane ellip xpolar xyz tria quad linear tube surface label note that the surface property is a special kind of label the complete surface information the surface groups to which the surface is added Surface id Surface type Label Complete info groups Figure 2 48 Surface information When a grid block edge is selected its information is displayed as shown in the figure 2 49 The block edge information consists of the block index the edge index within the block and the density of the edge Block Edge index lo Edge density 9 Figure 2 49 Grid block edge information 33 The grid sheet information is very limited because the grid sheets pass through various blocks of the grid and the list of these blocks may be huge depending on size of the grid A grid sheet may not be linear and hence it doesn t just contain x y number of points on it to display its size Hence the only useful information that can be displayed is whether a grid sheet is a surface sheet or not ls a surface sheet No Cancel Figure 2 50 Grid sheet information 2 3
42. the 7 dialog box of each tool opens In the left side workplane toolbar is located Bottom bar shows status messages details of the grid option to toggle through surfaces and short help The messages related to the operations you perform in the GUI can be seen in the status bar Each tab has its own importance that helps in guiding the gridding process In gridding process you firstly deals with surfaces which lead to us to our first tab 1 e Surface tab The Surface tab contains operations which allow you to create surfaces and edit surfaces for use in GridPro Along with creating and editing the surfaces tools that allow repairing the loaded surfaces are also located in right side panel In right side panel surface grouping tools are also located All these tools will be discussed later File View Help Surface Tools Solver amp Surface J Topolog Grid Property i ER DET ay 4 mw a A mAN Oo owes ag New Save Delete Frame Snap Pick All Current Wireframe Surface Ggrid Validity soa QQAaeS rk B amp B TBS Load Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Start kF boaii Fit 1 Stop Fit 2 Plane Cylinder Ellipsoid Periodic 5 mana Od o S Bi Fix oR Hae p akz leloba 3 Eoia Mede I Smeth at n Center Handle 03 Num Cells 0 ll surtace 140 zil Tag Topology State v Help Figure 2 2 Surface tab You don t want to view all the entities in t
43. the first corner group corners and then switch on the other group and select all the corners in that group The corners of one group will be mapped onto the other when reflected about the 143 periodic axis GridPro will perform this map if we assign the two boundary corners separately Period button works only if the current surface is a periodic surface otherwise an error message pops out as shown in figure 4 108 Current surface is not a periodic surface Cancel Figure 4 108 Error message 4 9 5 Check Check Ge button allows you to check the assignments of current surface It displays only the corner assigned to the current surface All the corners except the corners assigned to current surface are hidden Assigning corners to a surface is a process where you are very prone to make mistakes by assigning corners that are supposed to not As you know that the surface assignment corners of a current surface is highlighted with a white dot you switch on this button and scroll through the surfaces and check which corners are assigned to each surface 4 10 Surface Building Utilities Many a times you need to create a surface internal surface most often in GridPro using the corners and edges The use of internal surface is to capture the slope discontinuity in the geometry or the sharp features in the geometry To do so the internal surface should exactly pass through the slope discontinuity of the geometry And this surface should
44. the number of triangulations have to be reduced without compromising the surface shape in order to increase the GUI performance Thin button helps to ap reduce the number of triangulations on the basis of angle or ratio Thin Thin button is located in right side toolbar under Edit section in Surface tab If clicked a dialog box opens as shown in figure 3 21 In the deviation field specify the maximum allowable surface cell angle In the ratio field specify the ratio by which the number of cells have to be reduced Any one of the options can be specified if both specified it will try to reduce the number of cells in an iterative manner to satisfy both the conditions Figure 3 22 shows a surface with and without thin While thinning the surface ensure that the surface shape is not lost Reduce the angle ratio to avoid losing the surface shape Ratio 0 2 Deviation in deg 5 Output file Select file Ctrl F Cancel Apply Figure 3 21 Thin dialog box 69 A A SSA gt Ae ETN re ARV vay NKY Ny mi Aan A a aa A J J Wy LER flee Nip coal RL SAR PNA VA an A ESIC WOOK RASD IY NK Ns Ys WAKE i KA fA ON a w K mas vy Lv vi a PENA e 4 aN v A Yay L Vat Ma A a ae en TA Ta a vave aT at P ZS J ave Y RA Oo wa 4 a SLEE AT T tate TATENA re L at r rs Vr AVATATATA YA a Va FAVATATATA TA VV UK TAIRA si SAT AY KI Par SANIYE K
45. the plane The normal of a plane helps to define the plane s orientation For visualization purposes the infinite plane is displayed as a square of finite size Apart from the center and normal the plane size is also required to create the plane surface It s just a visualization parameter The larger the size the larger the rectangle will appear In order to oO input a plane click on the Plane Plane button in the 3D tab of Create section in Surface tab The Create Plane dialog box as shown in figure 3 3 appears on the right side panel Center 0 Normal 1 Size 1 Get workplane parameters Cancel Apply Figure 3 3 Plane dialog box The fields corresponding to center normal and size of the plane can be manually edited The plane normal and the center field require three real numbers separated by a space which represents the value on all three coordinates in the order x y and z and the size field requires a positive real number which is taken as the diagonal length of the plane After inputting the co ordinates for plane click on Apply to create a plane in GUI The newly created surface would be the current surface shown in sea blue color The workplane of current graphics window data can also be used to create the plane surface by clicking on the Get workplane parameters A workplane is defined by its center normal direction and size of it length width This data is directly copied to the fields 57 correspon
46. then it is called mildly severe corner and the singularity is mildly severe singularity In 3D if there are 3 or more faces emerge out of an edge then it is called mildly severe edge NOTE The above explanation is applicable only for the corners at the surface intersection In other words it is applicable only for the fixed corners Figure 4 90 Mildly severe topology 130 e Mediumly severe singularity The corners which are being assigned to the external surfaces should have two adjacent blocks on either one of its normal sides whereas in case of internal surfaces it should have two blocks on both of its normal sides In other words there should be three edges emerging out of the assigned corner in case of external surfaces and 4 edges emerging out in case of internal surfaces in 2D For 3D instead of edge emerging out of a corner it would be a face emerging out of an edge From the above explanation if there are 4 edges emerging out an assigned corner for an external surface or 5 edges emerging out for an internal surface in 2D is called mediumly severe singularity NOTE The above explanation is not applicable to the corners which are at the surface intersection In other words it is not applicable to the corners which are having more than one surface assignments Figure 4 91 Mediumly severe topology e Very severe singularity From the above explanation given in the mediumly severe if there are only 2 edges emergi
47. to extrude copy the existing wireframe GridPro c s m provides the Copy e8 tool with 3 options which is located in the Edit section of right side panel in topology tab Figure 4 65 shows the Copy Wireframe dialog box The Copy button options allow you to produce transformed copies of the current corner group by using the workplane A group must be activated to use this button The first operation With Links represents perhaps the often used tool This operation in addition to translation of the grouped corners links the duplicated set of corners to original set of corners Essentially the With Links operation saves you time because the operation creates a duplicate of a wireframe in a different plane then creates edges between the wireframe and it s duplicate automatically The second operation Links amp Projection defines another often used feature This operation duplicates the active group by first moving its center of mass to the workplane center and then projecting each corner onto the workplane in the direction of the original movement Then links the original corners to the corners which compose the flattened copy of the group The Links amp Projection operation has tremendous value inputting corners along a curved trajectory seldom can be accomplished with the same efficiency using other operations Like the other two operations in the Copy dialog box the Link amp Projection operation adds duplicated corners to t
48. which you want to save Save a corner group saves all the surfaces in addition to the specified corner group Entire topology Corner group As ws fra To another directory Figure 2 31 Save drop down list in topology tab Another option Save DAs _ws fra option in the Topology tab allows you to save a topology under the file name _ws fra until you overwrite the file This is the file that is used by the grid generation process and each time you start the grid generation GUI automatically saves G G 6 the file to _ws fra name The 4 _ws fra file has four backups ws fra 1 ws fra 2 _ws fra 3 and _ws fra 4 When you save a new file to _ws fra the last file saved under 4 _ws fra becomes a backup file and the oldest backup file is erased In essence GUI saves five files under the _ws fra name then erases them as new _ws fra files are saved It is possible to save the topology to another directory by using Save gt To another directory gt in Topology tab which allows you to save the topology to another directory 1 e the wireframe and the associated surface files It s helpful for extracting files related to your topology and copying to another directory GridPro saves grids to the default file name as blk tmp To assign a user defined name to a grid use Save DAs elementary grid i in the Grid tab By altering the file name you will be 2
49. will retain the same unless the user changes it When you finish inputting all these values press Apply in order to implement your input as shown in figure 2 73 The workplane should immediately conform to its new properties The workplane center can also be defined based on a corner id The corner id can be found from the corner information pop up The selected corner id s position acts as the center of the workplane and user can define normal and size of the workplane X axis Y axis Center 0 0 Pick a corner as center Corner id 0 Normal 0 0 Size 1 Cancel Figure 2 73 Define Workplane Parameters dialog box 2 4 2 Workplane Group fit In three dimensions you will almost surely use both corner groups and the workplane that are useful in creating topology with ease Therefore GridPro provides you with the operations that integrate group and workplane features Mastering these operations will help you maneuver quickly and efficiently in the GUI Often you might want to align the workplane with a group of corners that can be used for copying or moving in all three directions Fit operations are used for this purpose These Fit operations align the center of the workplane with the center of mass of the active group The Fit to group option under set menu aligns the center of workplane rectangle with the center of mass of en Te 7 z l the active group The fit buttons fitl S fit Sa fit3 id centers th
50. 11 All You can turn on the visibility flags of all the surfaces of the topology by using ALL button Q All Note that the surface groups act as a final layer of filters and only the surfaces in the current reference surface group are visible The surfaces which are hidden using the right click surface menu are also visible after this operation 2 3 12 Current Similar to turning visibility flag on for all surfaces you can turn the visibility flag off for amp all surface excluding the current surface by using CURRENT ent button But the current surface is always displayed using a special flag Hence all the surfaces except the current surface are invisible When the current surface is scrolled the new current surface alone is displayed and rest all surfaces are hidden including previous current surface 2 3 13 Select K You can also pick a surface to be Current Surface by using Select button Select Depress Select button and click on the desired surface you want to select as current surface Its color would be changed to sea blue color and its id would be updated in the index field 2 3 14 Display Surfaces geometries and grid can be viewed in various modes for better visualization and a clear picture of these objects The modes in which it can be displayed are 34 1 Shade with HLR All 2 Shade Cp Shade with Hidden Lines Rernoved 3 HLR Shaded 4 Lines Li 5 Points ae at Points 6 1 1 0th points t
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52. 5 Carry assignment No assignment Figure 4 50 Different surface assignment propagation type Switch to Internal Faces tab in Wrap dialog box Figure 4 51 shows the dialog box of the internal wrap Since it is a wrap which is inserted inside an existing topology it takes care of the assignments and hence outputs a valid topology Enabling Add insert will add an insert in the middle of corners used for wrap and the wrapped corners nternal Faces Offset length 20 j Add insert Cancel Apply Figure 4 51 Internal wrap dialog box 4 3 Topology Grouping Utilities One tool that helps you create three dimensional topologies is the workplane another tool is group Often you will repeat procedures for creating topologies because grid topology often requires the user to repeat operations GridPro has developed the group feature in order to help you circumvent the procedural repetition so prevalent in the field of grid generation 106 More than any other feature groups help you manipulate three dimensional topology and use graphics effectively Creating a typical topology composed of hundreds of corners and edges without utilizing groups is ill conceived time consuming and unnecessary Similar to topology groups you can group surfaces also Surface group are as much useful as corner groups as it helps you to differentiate groups of surfaces from all the surfaces loaded into GUI 4 3 1 Corner Groups Before learning what
53. 5 able to retrieve your file whenever you wish because all other grids generated in the working directory will be saved under blk tmp A As elementary grid H Trimmed blocks as grid i Current sheet as quad Figure 2 32 Save drop down list in grid tab GUI also enables you to save certain blocks and sheets just as it allows you to save grids To save a set of grid blocks select the grid as current activate the set of blocks then select the Save Trimmed blocks as grid i option in the Grid tab Similarly to save current grid sheet select the grid as current select the sheet you wish to save as current sheet and select Save PCurrent sheet as quad i in the Grid tab This grid sheet would be saved as quad format which can be loaded into the GUI using Load gt Surfaces option Num Blocks 0 al AC ch Mum Cells 0 Surface id 10 gt te Figure 2 33 Tag Topology State Apart from these save options you are provided with one more save option called Tag Topology State which can be located at the right side bottom in the status bar as shown in figure 2 33 It can be used to tag a state in other words tag before after an operation in a file This will not be saved as a separate file in the working directory but saved inside the fra Tag Current Topology State file These tags can be reverted back to previous operations Revert to a Previous State which is similar to undo while wo
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55. Figure 4 85 Before and after aligning on workplane 4 6 5 Align On Workplane Center The Align on Workplane center operation translates the center of mass of active corner group to the center of the workplane Figure 4 86 Before and after aligning on workplane center 127 4 7 Topology Enhancing Utilities Topology enhancing utilities are used to modify the topology in order to get a better quality grid GridPro offers a tool called Heal which automatically fixes the region in the topology where the quality of the grid would be bad Before getting into the fixing singularities you need to know what singularity is Singularity In 3 d a regular grid point in a structured grid has 6 neighboring grid points which form a well defined index coordinate system For multi block structured grids most of the grid points are regular However singular grid points are introduced for steering the grid lines to better fit a complex geometry Singularities can be classified on the topological level instead of for grid points There are two types of topological singularities singular block corners and singular block edges A singular grid point is either on a singular corner or on a singular edge For 3 d cases the term singularity usually means singular edges On the other hand for 2 d singular corners are the only type of singularities A singularity 1s ranked with the number of neighboring blocks For internal edges i e edges not on surfaces
56. GridPro GUI Manual Version 1 0 re Y GridPro Superior Engineering Solutions Program Development Corporation 300 Hamilton Ave Suite 409 White Plains NY 10601 Tel 1 914 761 1732 Fax 1 914 761 1735 Web www gridpro com E Mail gridpro gridpro com September 24 2014 Copyright Program Development Company 1992 2014 Licensed Materials All Rights Reserved This document contains proprietary and confidential information of PDC The contents of this document may not be disclosed to third parties copied or duplicated in any form in whole or in part without the prior permission of PDC The contents of this document are subject to change without notice and do not represent a warranty on the part of PDC CONTENTS Chapter 1 Introduction 1 1 1 2 What is GridPro How GridPro works Chapter 2 Getting Started With GUI 2A 2 2 23 2 4 2 3 2 6 Introduction to GUI Top Menu Bar Global Dock Workplane Toolbar Toggle Surface Section Toggle Display Section Chapter 3 Surface 3 1 3 2 3 3 3 4 Surface Types Surface Orientation Surface Probing Utilities Surface Reconstruction Utilities Chapter 4 Topology 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 Topology Building Topology Creation Utilities Topology Grouping Utilities Topology Modifying Utilities Topology Transformation Utilities Corner Aligning Utilities Topology Enhancing Utilities Topology Optimization Utilities
57. I d hes wees Figure 4 9 Topology with wrap layer highlighted Figure 4 10 displays the full wraps in dark shade from the first example in this chapter 88 Figure 4 10 Topology with wrap layer highlighted In order to develop an intuitive understanding of what topology to create you should learn through example You will successfully prepare regions for gridding by first learning the rudimentary rules described above Of course in order to obtain the phenomenal grid accuracy GridPro can provide you have to learn gradually the nuances of different surfaces and be able to produce topological frameworks using intuition rather than rules All real life configurations have three dimensions Therefore in order to use GridPro effectively you must understand the structure of three dimensional topology and become proficient in manipulating three dimensional topology The approach to wireframe building is of two types one is top down and the other is bottom up Anything can be followed for any case but it is advisable to use bottom up approach for complex cases 4 2 Topology Creation Utilities As discussed in Chapter 4 the tools related to the topology which is grouped under different category Of which the first category is the topology creation utilities grouped under Create section of Topology tab located in the right side panel as shown in figure 4 11 Topology creation utilities include Corner Link Insert Macro and Wr
58. In this toggle display section under the surface branch there are three sub branches such as Feature edges Border and the Path selection The feature edges are the lines highlighted on the surface triangulation where the given feature angle exceeds which is highlighted in baby pink color The border is the path around the border of the surface that is highlighted in olive color and the path selection is the path selected on the surface by the user using the path tool bar to segment the surface These tools are explained in detail under section 3 4 Each one is provided with a check box which will hide show the respective option The surfaces can be toggled by unchecking the surface check box as shown in figure 2 80 To toggle a particular surface option expand the surface main branch and uncheck the check box of the corresponding option We Display a Surface Feature edges Border Path selection Figure 2 80 Surface sub menu e Topology There are various options to hide show the topology related objects such as Wireframe Corner id s and Error as shown in figure 2 81 By default topology is only visible in Topology tab in rest all tabs it 1s hidden Sometimes it might be desired to hide the topology to obtain a better view of its bounding surfaces The topology can be hidden by unchecking the topology check box The wireframe can be toggled using the check box of wireframe When the corners are hidden their indices ids are a
59. RRAN SS Wes ad BN aed mh Nea A A ENANA AEAN AY hy VR My val Ki NORA BERET SC eK N WV Ae es Uy tae a TAVAN AS ENA ar AY KENNI gt tan CATA a Ly i ve fr e antav a L h Ga a ata 4 va SZA HIT F Wave E KAS a Ti 5 ee TAr wat a IZ SF av ea y DE fae a rat rr ow LA Fs 77a Va WO Sane Si 4 A AV lt Sy Sc ra a ae IA S2 SS Svs WN DAE n bk K a VAN 7 3 Ap lt Bgry f Current Surface has been thinned using deviation as 0 2 and angle as 5 Figure 3 22 Before and after applying thinning tool 3 4 2 Split Any geometry which is loaded into the UI would be a single surface by default The surface has to be split into different pieces in order to capture all the features of it such as sharp edges GridPro has different ways of splitting of which the first option is Split disjoint surfaces e Split disjoint surfaces If in case the loaded surface has disjoint surfaces and yet represented as single surface the surface has to be split using Split disjoint surfaces first This would split the disjoint parts of the geometry into different surfaces Split disjoint surfaces is located under Surface Tools menu The tool works on active surface group hence the surface which has to be split should be grouped under a surface group and must be switched on while executing the command Refer section 4 3 for more information on g
60. Right click menu of point of that edge of grid block as center of rotation by selecting grid blocks center of rotation option after right click Similar to slice button you can add grid sheet at that particular point on grid edge by selecting add grid sheet option 158 Selecting Change density option after you right click on a grid block edge will enable you to change the density of the block in grid level which is explained in detail in section 5 3 aS eee You can also right click on a grid sheet which shows the menu as in figure 5 9 The grid sheet info option displays whether the selected Center of rotation option is a surface sheet or not Similar to picking the center of rotation Make current on a surface wireframe and grid blocks you can also select it on the Hide grid sheet by selecting the center of rotation option from the right click Delete menu on the grid sheet You can also make any grid sheet as current Set property by clicking on make current option Similar to hide and delete a surface you can hide delete a grid sheet using the options hide and delete Once it is hidden it can be shown by checking the Display type Figure 5 9 Right click E ord aieei corresponding check box of the grid sheet in the grid sheets section which is explained in section 5 6 Assigning property for a non surface sheet would be difficult task in a complex grid because you need to be really precise in picking the center of each block face
61. ables us to perform a transformation on the world axes so that they correspond to the screen axes In the Snap option the Closest ts operation rotates the model such that the world axes go to the closest possible screen axes For example Closest might align the world y axis to the screen z axis the world x axis to the screen y axis and the world z axis to the screen x axis because that transformation requires the least rotation Snap can be used for snapping to XY YZ ZX YX ZY and XZ planes Similarly workplane axes can also be aligned to screen axes The option Workplane closest also works similar to closest option here the workplane axis is aligned to the closest screen axis 29 Closest Workplane X Workplane Y Workplane Z Workplane closest Define SrrrrhBrhEP P Figure 2 42 Snap drop down list You can also snap screen axes to user defined axes by using Define option nde Snap menu If selected it will pop out a dialog box as shown in figure 2 43 For that you need to input the orientation and up direction where orientation axis is pointing towards the screen and up direction is the axis pointing upwards The third direction is automatically calculated AXIS Y axis Orientation f 0 Up direction 0 Figure 2 43 User defined snap axis dialog box 2 3 8 Zoom Unzoom a Zoom Zoom and unzoom en helps in zooming unzooming a portion of the screen with respect to the center of the screen The right mous
62. ace Figure 4 41 shows the drop down list of the same The first option in 2D macro is Rectangle The Fig 4 41 Dimension drop down rectangle macro allows you to create automatically a two dimensional region bounded by 4 planes you must be working on the plane z 0 Since it s a 2D you only required 4 values x min max and y min max Figure 4 35 shows the dialog box of rectangle macro 101 Figure 4 42 Rectangle topology macro e Circle The Circle macro enables you to create a circular surface and its corresponding topology It can be created with a center and the radius Circle center in x and y co ordinates and radius need to be defined Figure 4 43 shows the dialog box of the circle macro Wiretrame Default X axis Center 0 Radius 0k Cancel Apply Figure 4 43 Circle dialog box Figure 4 44 Ellipse dialog box p 8 e Ellipse The ellipse macro enables you to create an elliptical region of any shape with a center axis and radius To change the shape of the ellipsoid change the radius value of axis and axis 2 By giving same radius value on both the fields you will create a circle Instead you can use 102 the circle macro Since it s a 2D surface only two coordinate axis 1s required Figure 4 44 shows the ellipse dialog box 4 1 5 Wrap A wrap is a dilated or shrunk duplication of a string of segments or quadrilaterals translated from and l
63. ace will be reflected in the grid which can be modified later in the property tab based to the desired export solver format if required Clustering parameters for a current surface can be set by checking advanced options in properties dialog box Checking advanced options enables the clustering parameters as shown in figure 3 35 Clustering parameters refines the region near surface boundaries E wall parameter is the off wall spacing used for clustering within the grid generation engine The Off wall spacing deals with the number of grid points on a local scale specifically near boundary surfaces The number you insert in the Off wall spacing field is the length of the cell edge measured between a boundary grid point and the next closest off wall grid point The ratio between this length and the cell edge length measured between the off wall grid point and the next off wall grid point is the number you input in the stretch ratio field This number becomes the ratio for a geometric progression of cell edges which propagates Orientation 1 sided with auto ort Property Default Advanced options E wall Off wall spacing Stretch ratio Multi grid Label Load the surface only once Ok Cancel Apply Figure 3 35 Surface Settings parameters with Advanced options enabled outward from the boundary surface along off wall grid points Typically the value of off wall spacing is less than 0 001 of the l
64. aces using wireframe Wireframe defines the shape of the surface Figure 2 23 shows the drop down list of the Surface Tools menu All these tools except for convert which will be explained below and Split disjoint surfaces which will be explained in section 3 4 2 are explained in section 4 10 20 Tube Controlnet Surface Controlnet Curves Feature edges Intersection of surfaces Ribbon Surface nest Internal surface Split disjoint surfaces Convert Figure 2 23 Surface Tools drop down list e Convert Convert is a file format conversion tool similar to Import options whereas this is specific to GridPro formats Figure 2 24 shows the available conversions Surface to Wireframe Wireframe to Surface Surface to TRIA Figure 2 24 Convert drop down list Surface to Wireframe Converts any surface Supported formats quad tria lin dat which is loaded into the UI and saves as a fra file in the working directory Opens a dialog box once it 1s selected where a surface group contains the surfaces to be converted should be selected in the respective field as shown in figure 2 25 Surface group Select group Y Ok Figure 2 25 Surface to Wireframe conversion Wireframe to Surface Converts a given corner group as a quad surface and loads into the UI Once it is selected Wireframe to Surface dialog box opens as shown in figure 2 26 where a corner group and an output file name has to be provided 21 Comer group S
65. add subtract etc cl shows previous selections while shows forward selection 4 3 5 Span out You can directly add or remove sheets of corners from active group by using span out or peel off button The drop list under this button is shown in figure 4 56 It has 9 options 5 options belonging to span out means adding corners to active group and 4 options belonging to peel off mean subtracting corners from active group Using span out layer 1 you can add one layer of corners in all direction connected to active group from the reference group Similarly you can add 2 layers or 3 layers or 4 layers of connected corners to active group from the reference group Reference group refers to the corners displayed as dimmed in addition to active group it depends upon your selection of group mode display A or R Span out all adds all the corners in reference topology to the active Span out 1 layer Span out 2 layers Span out 3 layers Span out 4 layers Span out all Peel off 1 layer Peel off 2 layers Peel off 3 layers Peel off 4 layers Figure 4 56 Span drop down list group This option is really useful for checking the connectivity between the topology If you have two distinct pieces topology you can separate that out using this feature Peel off works opposite to Span out Peel off subtract corners from an active group in a similar fashion as span out adds corner to active group Similar to span out to carry out peel off you
66. adrilateral elements while tria surfaces are composed of unstructured triangular elements A tube surface is a surface of revolution about a cartesian curve Except for tria surfaces all of these implicit and explicit surfaces can be created in GridPro Implicit surfaces are grouped under Create section as shown in figure 3 1 and 3 2 The surfaces can be either 2D or 3D l S B Default dimension tab opens for surface Create options List of surfaces can be created for 2D are aoe vee E AS eles Figure 3 1 2D analytical surface dialog box e Line e circle e ellipse e periodic and for 3D surfaces are e plane Plane Cylinder Ellipsoid Periodic e cylinder e ellipsoid Figure 3 2 3D analytical surface dialog box e periodic 56 Even though buttons are self explanatory they are explained below corresponding to their classification Starting with Implicit 3D surfaces 3 1 1 3D Implicit Surfaces e Planes Planes are categorized under 3D implicit surfaces Planes represent one of the simplest surfaces Planes can be defined either by an equation or by a center point and a normal direction The general equation for a plane is ax by cz d Q Planes are inputted in the TIL code according to this equation However the plane s center and normal direction is required in the UI Like the workplane surface planes are represented by rectangles The center of this rectangle is the point that helps define
67. all 3 directions Then rotation which can be defined similar to the rotation button by using rotation center rotation 122 axis and the angle of rotation Translation 2 field can be used to apply any surface translation after the rotation discussed Corner group Select group above is executed This option is helpful Surface group Select group when you want to scale the group with Translation 1 00 00 00 center other than origin You can translate kinm the group to the origin using translation 1 0 0 j 0 0 0 0 0 0 0 0 0 0 and apply scaling and then revert the topology back to the same position using a ia Gs Scale 1 0 Rotation center oo o oo o o 0 0 Rotation axis 1 0 00 j 00 Rotation angle oo o l Translation 2 0 0 0 0 0 0 dialog box to input a matrix below the ae eae translation 1 field By default the matrix Ok Apply form fields are disabled check the matrix the translation 2 Instead of executing the transformations step by step you can use the transformation matrix to specify the translation and rotation together As you can see there is a separate field in the check box to enable the input fields which Figure 4 76 Transform dialog box will obviously disable all the other fields except the corner and surface groups 4 6 Corner Aligning Utilities As you encounter increasingly complex topologies you may need to project align corner groups onto the wo
68. also cut the geometry orthogonally These surface building utilities which are grouped under Surfaces Tools located in Menu bar help you to satisfy the conditions in creating the internal surface 4 10 1 Feature edges Feature edges is the foremost tool to be used while creating the surface This creates corners on the current surface slope discontinuity using the surface nodes otherwise called as surface triangulation nodes Once the feature edges is selected from the drop down list a dialog box opens as shown in figure 4 109 You need to input the threshold angle to calculate find out where the slope discontinuities are By default it takes 40 degrees The feature angle will be calculated at every node on the current surface wherever it exceeds the given feature angle a corner will be created on that node which will be later linked with the corners created adjacent to it and also assigned to the current surface You can also include exclude the boundary edges of 144 the surfaces from using this utility Including the boundary edges will make the utility calculate the feature angle on the surface boundaries also and create corners if it exceeds This can be done by checking unchecking the include boundary edges check box Threshold angle _ Include boundary edges Figure 4 109 Feature edges dialog box 4 10 2 Intersection of Surfaces Intersection of surfaces option under Surface tools drop down helps in creating corners all conne
69. ap 89 File View Help Surface Tools Solver y a Topology acria iPropertyul LATO 2 Be ag Frame Snap Pick Current Wireframe Surface Ggrid Validity gGlmHmaQaqaQae rs amp s ew Load Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Start Sto A Corner Groups OEA Boe oe Fit 2 a kR it N A Doo om E aS Assignment v Fill Section Handle L Num Blocks 0 Num Cells aif surtace id 0 zili P 229 Topology stater Figure 4 11 Create section Help Tag Topology Tag Topology State 4 2 1 Corners Wireframe is created entirely by corners and edges Any two or three dimensional structure can be constructed with just corners and edges Corners are displayed as small orange squares as shown in figure 4 12 Edges are displayed simply as yellow lines with two corners as endpoints In order to input a corner switch on the Corner button les in the Create section of topology tab Figure 4 13 shows the Create Corners dialog box Select the mode of creation 1 e either using mouse click or by specifying the coordinates By default the mode of selection is set to mouse that is specified as Create On and using the mouse click the corner can be either created on the workplane or on current surface By default the flag workplane is selected and so the corners will be created on the workplane Figure 4 12 Wireframe 90 Sele
70. are in relation with the current surface So the appropriate surface should be made current before assigning unassigning the corners Refer section 2 5 to know how to make a surface current 4 9 1 Toggle The Toggle button is used to assign unassign corners to the current surface on an individual basis The corners of the topology can be individually picked up and assigned unassigned to the current surface of the topology A corner is eligible for picking only 141 if it is appended to the current corner group If none of the corner groups are active all the corners are eligible for selection If a corner which is already assigned to the current surface is picked it is unassigned and similarly when an unassigned corner is picked it is assigned to the current surface This is very helpful when the user wants to pick the missing assignments manually If there are no surfaces in the topology selected corners are just ignored So making the desired surface current is the foremost operation in surface assignments next comes the corners to be assigned has to be grouped Once the corners to be assigned is grouped click on the toggle button and pick the corners to be assigned one by one Each corner assigned to the current surface will have a white dot at its center This white box provides you with a visual indication of confirmed surface assignment which proves to be useful often when many surfaces and many corners are involved in a topology Wh
71. at of the grid can be ASCII Binary Binary output format is preferable if the topology is huge but an ASCII grid file is readily readable and can be modified easily if needed All the edge densities of the topology can be doubled quadrapled halved or quartered Density designates to cell count per edge When the density of an edge is halved or quartered the integer closest to the multiplied value is taken as the density of the edge In the schedule file density can be scaled by any multiplier not just restricted to 2 4 0 5 and 0 25 Output file format ASCII Change global density Default Dump frequency 10 Output grid file blk tmp Output dump file dump tmp Ok Cancel Figure 2 55 Grid schedule dialog box The dump frequency is the sweep interval after which the output grid is rewritten This 1s typically a multiple of hundred Then the output file to which the grid 1s saved can be specified The specified file would be written in the current working directory The log file and all other output files of Ggrid are always written to the current working directory A grid file with the same name exists Do you want to overwrite it Overwrite Input a new grid file name Figure 2 56 Grid file name confirmation dialog box 38 Note that if the specified grid dump file name is already exists in the working directory a confirmation pop_up will open as shown in figure 2 56 amp 2 57 to confirm whether to overwrite or ent
72. b You have the facility to display few surfaces in GUI ee and hide few surfaces The hidden surfaces in GUI are called inactive Figure 2 37 Delete drop surfaces The surfaces that are visible are called active surfaces You down list in surface tab can delete all the hidden surfaces at a time by using option Delete DInactive surfaces SP in the Surface Entire topology tab or in Topology tab You can delete all the visible surfaces by Corner group using Delete DActive surfaces Pin Surface tab and Topology tab sanin There is also an option available to group different surfaces You can dii Es access surface groups in different ways which will be explained in surface group section 4 3 You can delete a specific surface group by using option All surfaces i a amp amp amp amp Delete DSurface group BP in Surface tab or in Topology tab You Figure 2 38 Delete drop can delete all surfaces whether visible or hidden in GUI by using down list in topology tab Delete DAIl surfaces option in Surface tab or Topology tab All the topological entities wireframe surfaces in the GUI can be deleted using Delete DEntire 21 topology fr option in Topology tab It can be retrieved back into the GUI by using Undo option Similarly a current corner group can be deleted by selecting Delete PCorner group option lll As discussed earlier you can load multiple grids in the GUI The grid that you are manipulating or work
73. be increased or decreased by a ratio Sparsen option can be used which is the third tab in the Density dialog box The dialog box of the same is shown in figure 5 16 Provide the ratio by which the density of whole grid has to be changed along with the output file name Click on Apply to load the new grid Use a ratio less than 1 to sparse the grid and more than to refine the grid Similar to Matching option Sparsen will also create and load a new grid file and switch off the old grid file g Sparsen Sparsen ratio 0 5 Output file out grd Cancel Apply Figure 5 16 Sparsen tab dialog box 162 Multiple grid files with an arithmetic or geometric increment decrement in ratio can also be generated by using Multi option which is the last tab in the Density dialog box The dialog box of the same is shown in figure 5 17 Provide the ratio and number of grids need to be created and select one of the increment method 1 e arithmetic or geometric Input the prefix of output grid files The output file name will have a nomenclature prefix ratio_used_for_sparse tmp You need to load the newly created grid manually Sparsen ratio 0 5 No of grids 2 Progression Arithmeti Prefix loutput_ Cancel Apply Figure 5 17 Multi tab dialog box 3 0 2 Mirror Another feature which can create reflective or periodic copies of a grid is Mirror This option is also located in the Tools section If clicked on Mirror option
74. be provided in the fields given next to rotation center which requires x y and z coordinates and the axis of rotation should be provided in the fields below the rotation center The pitch can be provided in the corresponding field which helps in revolving the wireframe in a helical structure And finally if you want to link the first and the last copy of the wireframe NOTE other adjacent copies are linked by default you can enable the checkbox at the end Sometimes a part of the geometry alone looks like periodic but the other parts would be linked with it In such cases you cannot do a periodic topology because you need topology on all periodic surfaces in order to continue the topology for the rest of the geometry For e g blower where the blades are placed in a periodic manner but you would like to have a mesh for the outlet even For such cases GridPro offers a tool called periodic to regular which can copy duplicate the topology created for the part into a full topology just like how a part of periodic geometry is gridded and revolved to get a full grid This option is embedded in the Sheets tab itself as a check box enabling this check box will disable all other options in that tab To use this option you need to create wireframe for the part of the periodic surface and then rotate it to the full geometry which will use the periodicity given for the periodic surface Once it is rotated fully the periodic surface will be removed from the UI
75. bon corner need not be created normal to the surface intersection The inverted surface group is the corner group which contains the corners whose normal should be reversed before creating the ribbon corner The ribbon corner created from those inverted surface group will be using the negative normal direction Out of these 3 groups path group is must while the other two are optional Similarly the corners in the path group should be assigned at least to one surface in order to find the normal The number of smoothing is the number of times the smoothing algorithm has to be run on the ribbon layer The ribbon width is the distance between the input corners and the ribbon layer corners 4 10 4 Ribbon nest Many a times the nodes on the surface are more in order to get the shape of the surface correct which in turn ensures good quality grid So the number of corners created by feature edges and ribbon would also be more Working with more number of corners to build the wireframe for the surface would be difficult and also time consuming process So it is advisable to reduce the number of corners To do so GridPro provides a function Ribbon nest which creates a given number of layers with reduced number of corners in each layer without affecting the normal of the ribbon generated This process of reducing the number of corners is also called as reverse nest Reverse nest is used in case of 2 dimensional reverse nest while ribbon nest is used for dimensi
76. cted by edges on the intersection of two or more surfaces Once selected a dialog box opens where you need to input the surface group which contains the intersecting surfaces Every corner created is automatically assigned to each of the intersecting surfaces Also there are no restrictions on the type of intersections you can contour with corners Surface group containing the intersecting surfaces Select group ba Cancel Figure 4 110 Intersection of surfaces dialog box 4 10 3 Ribbon Once the corners are created on the slope discontinuity of the surface or on the intersection of surfaces it needs to be extruded normally inwards Path group Select group or outwards that will satisfy the condition of ee ee a Special group Select group Y orthogonality for the surface created on the Inverted surfaces group Select group Y slope discontinuity Ribbon creates a layer of i corners either normally inwards or outwards to the Num smoothings 5 given set of corners with the given width based on Ribbon width for the given corners and its assignments Once Ok selected opens the Generate Ribbon dialog box as Cancel shown in figure 4 111 The path group is the corner Figure 4 111 Ribbon dialog box 145 group where the corners created by the feature edge intersection is grouped This corner group is used to create the ribbon layer out of it The special group is the corner group which should contain the corners whose rib
77. cting the Current surface flag under the Create on tab allows you to input the corners on CURRENT surface Once the mode of creation is set click the left mouse button at the desired location on the workspace An orange square should appear at the location of the cursor You can also create by depressing the lt C gt key and click the left mouse button on the workspace Edges can then be created after corners are created the workplane has no effect on edges Create on Workplane Surface Figure 4 13 Corner dialog box If the workplane is perpendicular to the screen when creating corners on workplane an error message pops out as shown in figure 4 14 because corner cannot be created when workplane is perpendicular to the screen Cannot create corner Please check the workplane orientation Cancel Figure 4 14 Error message when workplane is normal to screen Similarly an error message as shown in figure 4 15 pops out when the corner creation mode is on the surface but the clicked position is outside the surface Cannot locate current surface under the cursor Cancel Figure 4 15 Error message when cursor is not on surface Many a times you would like to create the corner exactly at a particular location instead of arbitrarily In such circumstances you can switch the tab to Specify as shown in figure 4 16 and enter the coordinates in the provided fields and click apply to create the corner 91 Coordinates A Y
78. ction but in a cylindrical or helical path When you have a same cross section you can create a _ Periodic to Regular Corner group Max angle 0 270 Num instances 10 Min angle Rotation Center Select group Bd o sj o 0 Rotation Axts J Jn Pitch distance 0 _ Link first and last copy Cancel Apply Figure 4 72 Faces tab dialog box 2D wireframe on a plane and then copy it to the end of the cross section using the copy drop back edges button if it is on the same axis But when the axis is changing in a cylindrical or helical path it becomes difficult to copy and move it to position the wireframe approximately to the geometry So in such cases the Sheet rotation can be used to copy the wireframe Figure 4 72 shows the dialog box of the Faces tab The corner group contains the wireframe to be revolved Next is the minimum angle which represents the minimum angle from which the rotation has to be started Then the maximum angle till which the wireframe has to be revolved can be provided in the next field The number of instances is the number of times the wireframe has to be revolved within the mentioned angle and the angle is 120 divided equally for each instance For e g if the instance is 2 then you will have the wireframe at the starting point and then at the ending point if its 3 then you will have one more layer at the middle of the two end points The center of rotation can
79. d a limit so to position the object back to the screen display you can use Frame button fame located in global dock Frame Current surface option will change the view to current surface The current surface will fill up more than 80 of screen display Also center of rotation is set to center of surface It is 28 useful when your current surface is relatively smaller than the whole topology and you can locate it easily using this option Similarly you can frame to current group of surfaces using Frame Current surface group Similarly frame can used for Frame Entire topology or Corner Group in Topology tab The drop down list of frame button in surface and topology tabs are shown in figure 2 40 amp 2 41 respectively Current surface E Current surface Current surface group n Current surface group Entire topology Figure 2 40 Frame drop down list Corner group in surface tab Figure 2 41 Frame drop down list in topology tab In Grid and Properties tab Frame button can be used for framing a grid 2 3 7 Snap The GUI provides the option to align world axes or workplane axes to the screen axes The screen axes are fixed to the screen the screen X axis travels left to right the screen Y axis travels bottom to top and the screen z axis travels out of the screen The world axes are fixed to the model ain They can be translated and rotated relative to the screen axes The Snap button P located in global dock en
80. d corners In addition Ea and C you can add or subtract corners by picking a corners using button All these operations buttons will be effective for only one operation 1 e you can drag only once using this operation If you want to add subtract more corners repeat the procedure If button is depressed clicking on a corner which is not in the group will add to the group and clicking on corner which is already there in the group will subtract that corner from the group This operation is persistent it will be effective until it is switched off manually again by clicking on it 107 The next two intersection and kill operations help you more efficiently add corners to or remove corners from groups When a group already containing corners is active depressing the E button allows you to drag a red box with the right mouse button Any corner s inside this box that is part of the active group will be selected and all the other corners outside the box get unselected no matter what their position or state will be cleared from the group if they are not already added in the group When a group already containing corners is active pressing the x button will automatically subtract all corners in that group It clears the selection of respective group The button Similar to equal sign acts likes a solution of addition subtraction and intersection of corners of different groups It can do multiple addition of corners from spec
81. ders of the object The grid generated within the given period can be used to generate a complete grid across the periodic boundaries Similar to any other surface appropriate corners must be assigned to the Xpolar and XYZ surfaces Unlike other surfaces user have to use the periodic assignment d button in the surface assignment section refer section 4 9 in the right side panel of topology tab when assigning corners to periodic surfaces Once the B Periodic dic button is clicked in Create section of Surface tab it show two tabs such as Xpolar and XYZ e Xpolar An xpolar periodic surface is defined by its periodicity orientation and center When D clicked on Periodic P 4ic button the Create Symmetric Surface dialog box opens as shown in figure 3 6 Origin is taken as the default center of the surface Orientation of the axis can be changed from the Axis drop down list as shown in figure 3 7 The center and orientation can be modified by the transformation of the surface In general the periodic surface requires a transformation for its appropriate orientation Transformation of surfaces is discussed in the section 3 4 Hence two parameters are required for the generation of a default xpolar surface which passes through origin of the global coordinate system are periodicity of the surface and axis alignment The periodicity of the surface should be a factor of 360 Periodic surface can be used only once in a topology
82. ding to center normal and the plane size Note that graphics window is active even when this dialog box is open and hence the workplane can be resized reoriented if necessary and then the workplane data can be used e Cylinder Cylinder is also classified under 3D implicit surfaces It is a special case of ellipsoid whose radius is along one of its axes When clicked on Cylinder 4 button Create Cylinder dialog box appears on the right side panel as shown in figure 3 4 The center major and minor axis and radius along those axis the axis of the cylinder and power of the cylinder define a cylinder A cylinder is infinite in its length but for visualization purposes its length or view scale is also required The radius power and length field require a single real positive number which represents the radius on two axis power determines the shape or cross section of the cylinder Circular elliptic etc and the length defines the length of the cylinder displayed in the graphics window The center axis and the length direction field require three real number separated by a space which represents the coordinates of x y and z axis for the corresponding input Size X axis Y axis Z axis Center 0 0 o l Ais 1 0 lf Axis2 0 0 Length dir 0 fo Radius 1 Power 2 Length 1 Get workplane parameters Cancel Apply Figure 3 4 Cylinder dialog box The workplane data can also be used to create the cyli
83. e a dashed red line will appear signifying that the face is excluded Face exclusion is covered extensively in later section A wrap is better understood by sight than by explanation However the definition provides a good backdrop to the pictures Figure 4 45 illustrates wrappable one dimensional objects and figure 4 46 illustrates unwrappable one dimensional objects Figure 4 45 Wrappable 1D wireframes 103 endpoint of endpoints three edges of three edges mo comnecting siring isolate t comer polygon not closed Figure 4 46 Unwrappable 1D wireframes GridPro can automatically wrap pieces of a wireframe in one swift topological action you do not need to input the corners and edges of a wrap one by one However these pieces of wireframe must be wrap able and must be inside a group If these conditions are met you have a wrap able group In order to wrap a group switch on a corner group Refer section 4 3 and then press the Wrap button located in Create section The button opens a dialog box shown in figure 4 47 By selecting one of the values in the dialog box you can dilate or shrink your wrap by the percentage shown In status bar you will be informed if a group is wrap able or unwrap able Boundary Faces Intelliwrap _ Carry assignment O No assignment Wrap length Ok Figure 4 47 External wrap dialog box There are two kinds o
84. e as it is commonly used at various stages of topology creation Once a valid topology is built the grid generation engine can be used to get the structured multi block grid The grid generation engine Gerid can be started using Start gt t icon located in global dock Ggrid runs on the topology of the current graphics window of the GUI If there is no topology an error message is popped up as shown in the figure 2 53 If Ggrid is already running an error message is displayed asking the user to kill the existing one as shown in figure 2 54 GridPro will refuse to begin the gridding process if a topology is incorrect The errors include not assigning corners to surfaces not assigning corners to the right surface and failing to create wireframe quadrilaterals or hexahedrons Also the topology itself could be implausible for a given region If you make a mistake GridPro will guide you to that location by automatically turning on the error and highlight which serves to show your mistake Errors are displayed only when you attempt to start the eridding process of an incorrect topology Concurrently a more technical error message is also displayed in the command terminal 37 Invalid topology Cannot run Ggrid engine Kill the existing ggrid first Figure 2 53 Ggrid error message Figure 2 54 Ggrid error message e Schedule If the topology is valid a window will pop up to schedule the generation engine as shown in figure 2 55 The output form
85. e button can also be used for zooming in to a portion of the screen in order to dilate that portion for a more detailed view By clicking and dragging a box using the right mouse button you form a white zooming rectangle The point where you click is one vertex of this zooming rectangle As you drag the mouse the rectangle expands so that the line between the mouse s original position and current position is the diagonal of the rectangle When you release the button the screen zooms in on the specified rectangle 30 automatically If you have started to drag the zooming rectangle and then decide to eliminate it resize the rectangle as small as possible Most likely the rectangle will then disappear You can also use mouse scroll to zoom in and zoom out when you scroll out it zooms out and when you scroll in zooms in When the zoom or unzoom is done using mouse scroll the center of the screen is assumed as Zoom unzoom center 2 3 9 Pick GUI gives you an option to change the center of rotation based on your convenience The center of rotation COR is the point in 3D about which the camera is rotated in the visualization process Center of rotation is seen as small three axes represented in pink green and blue color in graphics window Note that this center of rotation is not used when zooming in out The center of RL rotation can be picked using Pick option located in global dock When the button Pick is selected any entity corne
86. e common to all the tabs 2 2 1 File menu File menu has seven options as shown in figure 2 8 About Check License Settings RET Working directory Import TE Export D Quit Ctri Q Figure 2 8 File Menu About option displays the software information as shown in figure 2 9 Software GridPro Version 6 1 22 Company PDC Phone No 914 761 1732 Ok Figure 2 9 About option displaying software information Check License option displays the license information If a valid license file exists in the GRIDPRO Ic mner directory a message pops out as shown in figure 2 10 A valid ws license for v6 1 11 is found Expires in 112 days Figure 2 10 License expiry status But if a valid license is not found a message as shown in figure 2 11 will be displayed If a valid license is not available contact GridPro support team at license gridpro com Same message is also displayed when UI is started and there is no valid license found ws license for v6 1 11 not found Figure 2 11 License status 13 From the Settings option you can change the predefined keyboard shortcuts font size background color and auto save frequency In GUI often used functions are defined with keyboard shortcuts for easy usage that can be modified The figure 2 12 shows the default keyboard shortcut keys These shortcuts can be modified using the drop down menu associated with each shortcut The allowed shortcut keys
87. e topology does not have to exactly fit the boundaries for the region to be gridded However the topology itself should be precise If a topology is positioned too far from a surface the gridding process might take longer than it normally should Thus as long as your topology is positioned with some care the surfaces will be gridded with relative ease When creating topology you would do well to remember this golden rule the topology for a region has to be precise but does not have to be positioned precisely just positioned to roughly follow the geometry of its bounding surfaces GridPro grids volumes in both 2 and 3 dimensions Although all real life objects are three dimensional sometimes two dimensional grids can serve as useful models 83 This chapter deals with the topology building and various tools which help in creating the topology These tools are classified based on their functions they are Creation Modifying Transformation Optimization Enhancing Projection and ot Oe a Grouping utilities All the utilities are located on the right side panel of the Topology Tab Under Create section buttons related to Topology Creation Utilities are located Under Edit section buttons related to Building utilities Transformation utilities Optimization utilities Enhancing utilities and Projection utilities are located Grouping utilities have dedicated section such as Group Topology consists of wireframe and surface assignmen
88. e workplane in all three axes with respect to different reference frames The Fit J operation aligns the center of the workplane with the center of mass of active group and also aligns the workplane normal axis to the shortest major group axis and the other two workplane axes to the other two group axes The 47 Fit 2 operation performs the same function 1 e align the center of workplane with the center of mass of active group but also aligns the workplane normal axis to the second shortest major group axis and the other two workplane axes to the other two group axes whereas the Fit 3 operation aligns the workplane normal axis to the longest major group axis and the other two workplane axes to the other two group axes Figure 2 74 displays how the workplane changes position for different fit options for the same group of active corners geo lt wortpiane k3 corners Fa V V Corner group fit Corner group Comer groups Comer groups K Corner group fit 2 Corner group fit 3 Figure 2 74 Group fit position for active corner groups 2 4 3 Fix The workplane center can be fixed to center of screen and it will update every time whether model is rotated or translated You can achieve that by switching on Fix button in workplane toolbar however the screen is rotated the workplane Z axis is always aligned with the screen Z axis 2 4 4 Center You can position the workplane center on any surface or any corner edge on the wi
89. ecause it works only on the current grid sheet When a grid line is clicked after pressing spacing button a red line connecting two nodes will be shown The length of the line or the node spacing is displayed in the pop up The spacing button proves useful when clustering is used in the grid It allows to precisely check the off wall spacing near a boundary mf 7 GridPro Workspace beta File View Help Surface Tools Solver e Ry wW Vv Ba v Z Z New Save Delete Frame Snap Pick All Current Wireframe Surface Ggrid Validity 4 All grids pry cx A Q A N D B bik tmp ER Load Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Distance between nodes 3 01259 ce a A tl surface ia 0 Jhi Ral Tag Topology State Help Figure 5 19 Spacing line with the distance pop_up 164 5 5 Quality Check Parameters Quality check is one of the most important post processing tool in the mesh generation Using a good quality grid will give more accurate results from the solver GridPro has a quality checking tool called Qcheck which is accessible from both command line and from GUI To check the quality of the grid click on the Quality button in the Tools section of right side panel of the Grid tab Once clicked Quality parameters dialog box opens as shown in figure 5 20 Clicking on Evaluate button will give a report on each parameter The individual parameters can also be viewed in a histogram b
90. ected by excluding faces You might believe that in order to wrap the outside faces of a three dimensional object you have to exclude the object s internal faces However GridPro automatically excludes these faces for you See figure 4 70 118 Figure 4 70 External wrap excluded the internal faces automatically Faces are not excluded Face exclusion doesn t have an exclusive button in the GUI It is accessible only using the shortcut keys In order to exclude a face you must hold down the lt F gt key and click two corners of a diagonal of the desired face A pink line appears between these corners signifying that the quad or face is excluded It is a feature in topology building before the grid generation process is started all the face exclusion pink line in the topology should be removed In order to remove the pink line hold down the lt F gt key select both the corners again Often exclusion markers will clutter your screen To remedy this problem you can hide the exclusion markers by unchecking error in topology tree of the toggle display section which is explained in the section 2 6 4 5 Topology Transformation Utilities Buttons such as Rotate Mirror Scale and General under Edit section are grouped under topology transformation utilities that will be discussed here 4 5 1 Rotate When Rotate ete button is clicked Rotate Topology dialog box opens as shown in figure 4 71 with two different tabs 119 e Gro
91. ection dialog box is popped up to select the new working directory as shown in figure 2 14 The dialog box allows you to create new folder directory and select them or select the existing directory 15 ji BASIC gt 1 SQUARE Organize v New folder sw Finais Name Date modified No items match your search J Libraries e Homegroup JE Computer hi Network lt Folder 1 SQUARE Select Folder Cancel Figure 2 14 File dialog box for working directory When the topology or grid is loaded from the different directory other than the current working directory the working directory will be updated to the recently used directory for loading the topology and it will be saved across the sessions This is not applicable if the surface is loaded from different directory The selected directory should have read write permissions Else the previous working directory is used If the default working directory has no read or write permissions a message as shown in figure 2 15 is displayed Failed to open file Users vijay qp_testing gp_utilities_gui _auto undo Permission denied Figure 2 15 Working directory read write permissions denied Import option allows you to import various geometry and grid formats into the GridPro UI Once the appropriate file is selected it converts the respective file to GridPro format and loads into the UI Figure 2 16 shows various import geometry and grid formats available in the UI 16 Geo
92. ed which is done by assigning appropriate wireframe corners to the respective surfaces This is called assignments or association in GridPro GridPro s mathematical engine relieves much of the tedious work of constructing the various parts of a grid and then properly assembling them With this technology users are not required to generate surface grids or build items such as block edges and their point wise distributions The user simply gets both surface and volume grids simultaneously and automatically GridPro employs a powerful proprietary Dynamic Boundary Conforming DBC technology which automatically morphs the topology wireframe grid into conformity with the bounding geometry generating a multi block grid The process is driven by the algorithms that ensure the highest possible level of grid quality available under the constraints defined by the user This quality level is difficult 1f not impossible to attain by traditional methods of multi block grid generation DBC technology enables high quality design optimization to proceed automatically As users make changes in region boundaries to achieve the desired physical attributes GridPro dynamically tracks the evolving boundary shapes Traditional approaches to grid generation are labor intensive and highly dependent upon user input whereas in GridPro it s vice versa CHAPTER 2 GETTING STARTED WITH GUI GridPro takes the grunt work out of grid generation The program has features that
93. ed as the one that is sea blue Current surface is central to corner assignment and a corner assigned to the current surface is shown with a white dot at its center Num Blocks 0 ee A Dp Num Cells 0 surface E MD Figure 2 78 Toggle surface section Tag Topology State Help 50 The backward scroll button ail is used to scroll to the previous surface 1 e the surface whose index is one less than the current surface and select it as the current surface of the topology Similarly the forward scroll button gt is used to scroll to the next surface a surface whose index is one more than the current surface Note that when the current surface is changed the index of the new current surface is shown at the bottom i e in the surface id field between the scrolls By providing a surface index or surface id in this field you can directly make that surface as current surface without scrolling Note that when the current surface is scrolled the corners assigned to the new current surface are automatically shown with the white dots When the current surface is scrolled it is always visible irrespective of the visibility flag of the surface But the visibility flag of the surface is not modified Hence the surface remains visible invisible when the current surface is scrolled further The current surface can be toggled using toggle KA button next to forward scroll When this button is clicked the visibility flag of the current
94. elect group the input corner group next to the Input group Refinements field Two optional features are also provided such as Flatness 0 1 00 feature corner group and smooth corner group which is NSmooth 0 inf T00 the part of input corner group Feature corner group TE Approximating _ creates the controlnet surface which passes through Smooth scheme Spring given feature corner group Smooth corner group Output Select a file smooths the surface in that given smooth corner group region using the smoothing scheme which is inputted Ok Cancel Apply in the Smooth Scheme field You can select the Figure 4 113 Controlnet Surface dialog box smoothing scheme from the drop down button next to smooth scheme In addition to this smoothing or 147 refining the whole surface can be done by inputting a refinement level in the Refinements drop down Surface created using high number of refinements is heavy in terms of high number of cells Depending upon your requirement it should be selected Usually refinements levels are either kept as 3 or 4 Refinement also tries to smooth the whole surface irrespective of smooth corner group You can define the flatness and number of smoothing required for your surface These parameters will apply on whole input corner group Similar to smoothing scheme you can select one of the three methods available to create the controlnet surface In approximating controlnet surface tries to
95. elect group Y Output file save as Q Figure 2 26 Wireframe to Surface conversion Surface to TRIA Converts a given quad or tube surface to a TRIA surface Once selected opens a file selection dialog box where the output file name should be given to save the tria surface Refer section 3 1 for more information on surface formats and section 4 3 on groups 2 2 5 Solver menu Solver menu in top menu bar is used for defining the solver format globally All the surface properties and grid properties will be assigned according to the solver format selected The various available solver formats can be seen in figure 2 27 List of solver formats for which GridPro grid can be exported are CFX4 GASP FIDA WIND STARCD FLUENT NCC CGNS DTF ACUSIM OpenFOAM SU2 Go PDC CFXd GASP FIDAP WIND STARCD FLUENT NCC CONS DTF ACUSIM OpenFOAM Suz Figure 2 27 List of Solver formats 2 3 Global Dock Once you open the UI all the buttons are disabled except for the New and Load button All the icons in global dock are discussed below 22 2 3 1 New When the UI is started Topology tab is opened as default tab Usually you start with an _ empty workspace which can be done by clicking on New button ew which is the first option located in the global dock If clicked it pops out a window asking for the dimension of workspace You can choose either 2D workspace or 3D workspace It will open an empty workspace with the
96. en the current surface is switched the white dot appears automatically at each of the corners assigned to the new current surface If you wish to deactivate a surface assignment click on Toggle button and select the assigned corner The small white internal box will disappear Though special tool buttons are provided for assignment and unassignment of corners the shortcuts S and Shiftt S are more comfortable and handy to apply these operations The keyboard shortcut S can be used to assign and similarly the shortcut Shift S can be used to unassign a corner which is assigned to the current surface 4 9 2 Add To assign multiple corners to the current surface simultaneously use Add Add button When Add button is active user can drag a box by pressing the mouse right click button to select the corners from the graphics window The selected corners which are not assigned to the current surface are assigned to it and all other selected corners retain their assignment Hence it makes sure that all the selected corners are assigned to the current surface Note that only the corners appended to the current corner group are eligible for selection If none of the corner groups are active all the corners of the topology are eligible for selection Also note that if there are no surfaces in the topology this operation is ignored Similar to Toggle button Add button can also be achieved using the shortcut key By holdi
97. endent of tabs if you toggle off the workplane in surface tab it would be still visible in Topology tab or any other tab 54 CHAPTER 3 SURFACE The foremost desired objects to generate a grid are surfaces Before gridding a region user must often read in several surfaces GridPro can read surfaces from roughly eight different formats Surfaces loaded into GUI must be analyzed and repaired if required so that it can be used for grid generation All operations related to surface restructure repair and surface preparation are done in Surface tab So starting with first tab i e Surface tab where you create the surfaces or prepare the already loaded surfaces that can be readily used for grid generation Surface tab provides you surface creating tools surface probing tools and surface reconstruction tools Each one is explained in different sections in this chapter Before you start working with surfaces you must know with which all surfaces GridPro works The surfaces in GridPro have two kinds of classification One is based on the format and the other based on the orientation Based on the formats it is classified into implicit analytic surfaces and explicit surfaces Based on the orientation it is divided into internal and external surfaces The surface classification based on formats is explained in detail in section 3 1 similarly the other classification is explained in section 3 2 In Surface tab tools are divided into three secti
98. enerated in GUI but it can be me loaded into GUI A tria surface a is composed of unstructured node 4 e triangle 2 triangular elements Each I traingular element is defined by triangle node 3 3 points The tria files are lt a represented by ftria as an extension A tria file is similar to a quad file that consists of node Figure 3 14 Tria surface with two triangular elements total number of points coordinates of each point number of triangular elements in the surface the node numbers of the elements and the property id of the surface No degenerated sides are allowed for any of the triangular elements Figure 3 14 shows an example of tria surface with two triangular elements Quad files generated in GUI can be converted into tria files using some conversion tools In addition to that the geometry formats such as step stl iges etc are converted to tria files using the conversion tools before it is loaded into the GUI 65 3 2 Surface Orientation As mentioned earlier surfaces can be classified based upon orientation The orientation defines direction of the normal vector to the surface The orientation of a surface determines the region to be gridded that is either in the region outside the surface inside the surface or both Thus the surfaces are classified as external and internal surfaces The external surfaces have grid only on one side either inside the surface internal flow geometry or outside
99. ength of the boundary The stretching value usually lies between 1 1 and 1 5 See figure 3 36 surtace normal spacing 005 stretch 1 1 al 006655 0 0073205_ 0 006655_ 0 00605 _ 0 0055 _ 0 006655 0 00605 0 0055 0 005 ry SS A N 0055 A E te a 0073305 Figure 3 36 Stretching value for grid points The parameter Multi grid ensures that the number of cells in the normal direction in the adjacent block is a multiple of this parameter It is a unique value for the entire topology and hence to change m grid parameter use a positive integer value Also a label to surface can be specified by defining the label in the field next to the label The parameter label is a tag attached to the surface A given surface can have only one label but 79 multiple surfaces can have same label name The flag load only once is used by the grid generation engine if two or more built in surfaces are identical in type location and transformation 3 4 9 Reload current Reload current is only applicable for implicit surfaces generated in the GUI It is used to reposition or modify the surface parameter inputs for the CURRENT surface built in surface If the current surface is a built in surface the respective surface s dialog box opens in the right side panel If it is not a built in surface an error message is popped up as shown in figure 3 37 Note that the changed position specific to builtin surfaces using
100. ensity Figure 4 97 Nesting structure There are few requirements needs to be taken care in order to do the nesting efficiently They are 1 A five point singularity corner cannot be used in either high or low density group 2 There should be one to one connectivity between Low Density Group and High Density Group 3 Nesting cannot be applied for 3 D as it may encounter a singular point As shown in figure 4 98 it cannot be applied along 3D sheet 4 Nesting can be performed along 2 D sheet only and it is applied in 1D as seen in figure 4 99 136 Figure 4 98 Topology where nesting cannot be applied Figure 4 99 Topologies where nesting can be applied e Area Nest Area nest is similar to the forward nest tool where nest is applied along one direction but in the area nest it is applied on 2 directions simultaneously Figure 4 100 shows the dialog box of area nest tab Unlike forward nest Area nest requires only 3 inputs such as high low density group and the number of refinements Since the nesting is on 2 direction it does not require direction group It first applies nested refinement in one direction and takes those corners and applies the next refinement in the other direction Hence it is named as Area nest All the requirements mentioned in the nest are applicable for the area nest also except for the last one 137 since area nest is applied in 2 directions Figure 4 101 shows an example of how area nest
101. ensity of the topology edges 134 you increase the Gegrid processing time by a factor of 4 For three dimensional grids every time double the density of the topology edges you increase the Grid processing time by a factor of 8 If you have initiated the Ggrid process but notice that you wish to change the density of your grid you can do so without interrupting Ggrid As Ggrid is running change the density to the desired value using the Density button then select the Gridden option under Ggrid drop down in the Topology tab which is explained in section 2 3 Ggrid will automatically update the grid being created 4 8 2 Nest Nest is very useful when you are handling geometries with large scale differences It automates the creation of topology to achieve nested refinement in a simple and efficient way Conventional meshing techniques on geometries with scale differences create grids with large aspect ratio especially near the smaller features Improvement on the aspect ratio can be done by increasing the density throughout the geometry to capture the geometry of a smaller scale The refinement near the geometry is necessary but limiting because refinement propagates to the far field This limitation can be overcome by using nesting It helps to increase number of grid points near the geometry of concentration locally with one to one connectivity without increasing the points elsewhere The nested structure loops back blocks near the geometr
102. ent surface boundaries Similarly fit current surface group option uses the surfaces in active surface group to calculate the boundaries and fit workplane uses the workplane position and its dimensions Last setting option allows you to use the last used values for a macro in the current session The default option takes the predefined values i e 1 to 1 for min and max respectively The next six options increases or decreases the existing values in the fields below the resize depending upon the ratio you select You can also set the dimensions of these regions manually by changing the numbers in the X Y Z min and max fields Once the values are entered click on Ok to create the box macro and close the dialog box Clicking on Apply will create the box macro and retain the dialog box to proceed further Click on Cancel to close the dialog box without creating the box macro These three options work the same way for all the macros 99 Wireframe Surface only Figure 4 37 Box macro If either both Apply and Ok is clicked consequently or Apply alone clicked twice a warning message pops out as shown in figure 4 38 in order to avoid duplication of the macro again You can create a duplicate of the macro by clicking on Yes in the pop_up window Figure 4 38 Warning message e Cylinder Next option in 3D macro is Cylinder The Cylinder macro allows you to automatically create a cylinder with a center radius length and rotati
103. er a new file name Figure 2 57 Dump file name confirmation dialog box Similarly once you click on ok a confirmation pop up will open if there is a schedule file which already contains the same values in the working directory as shown in figure 2 58 You can either overwrite or use the existing one by selecting the appropriate option Aschedule file exists Would you like to overwrite rt Use exiting Figure 2 58 Schedule file confirmation dialog box The schedule file can be also edited by selecting Schedule option under Ggrid drop down list as shown in figure 2 65 e Disjoint Topologies If the current topology is valid but having disjoint pieces 1 e there are multiple independent pieces GUI provides an option to run Ggrid parallel over these independent pieces if the user have enough number of license Hence when GGrid is started for disjoint topology a dialog box will open as shown in figure 2 59 Figure 2 59 Disjoint topology confirmation dialog box If selected continue a disjoint grid dialog box will open as shown in figure 2 60 where you can input the prefix of output grid file names All the output grids their dump files log files etc are saved in the current working directory The sweep interval from the dialog box is used to output 39 the grid files once in every specified number of sweeps Note the output grids are all in ASCII format Prefix _disjoint_piece_ Sweep interval Figure 2
104. es aro Ml sutaceia o fie E Figure 6 6 After clicking on Show all property button ice Second button i e Show only Current button will hide all other properties except current property ezg File View Help Surf ceTools Solver r i I Property a a oR E E Q W v iS a g New Save Delete Frame Snap Pick All Cument Wireframe Surface Ggrid Validity G 9 a a 2 D B Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Stat Stop Nom Cels 47616 all surtaceia o fi Ep Tag Topology State Help Figure 6 7 After clicking on Show only current property button 178 Third button 1 e toggle all property button will flip the visibility of all the properties in that tab fi p ols my EARE om o N D 4 pe aed A SRO ie amp g New Save Delet Frame Snap Pick All Current Wireframe Surface Ggrid Validity Pe G SN on 77 A2aGB 2 BF BOG Lead Undo Redi Zoom Uraoom Probe Select Display Workplane Gad Start Stop tg Set Fit 1 Fit 2 a Fit3 E Fix ok Center amp Fill z Section on Handle Num Blocks 12 rr p Num Celts 47616 j Surface id 0 gt led Tag Topology State Help Figure 6 8 After clicking on Toggle all property button In the 3D properties tab all these buttons work in a similar way for the grid blocks All actions are independent of other tabs 1 e actions performed for the 2D properties tab will not affect the vis
105. f wrap one is external and the other is internal External wrap Boundary Faces is a wrap which extrudes from the existing topology either on positive 104 normal side or on negative normal side Internal wrap Internal Faces is a wrap which is inserted in between the existing topology and topology connections are adjusted such that the topology remains valid This is helpful when there is a need for local refinement without affecting the farfield boundaries Figure 4 49 Before and after Internal wrap The percentage of the wrap layer should be mentioned in the percentage field By default it takes 10 this value is the measure of the average length of all the edges in the corner group used for wrap It can also be adjusted using the slider provided before the input field The direction of the wrap can be chosen using the two icons ve and ve as shown in the dialog box The propagation type determines how the surface assignments have to be carried forward It consists of 3 options provided with a checkbox The Intelliwrap intelligent warp option removes the surface assignments from the corner group used for wrap and assigns it to the wrapped corners The Carry assignment option retains the assignments with the corner group used for wrap and also carried forward to the wrapped corners And the No assignment option retains the assignment with the corner group used for wrap and will not be carried forward to the wrapped corners 10
106. gning to grid If the grid blocking pattern is not matching with the topology an error message pops out as shown in figure 4 81 Figure 4 81 Error message 4 6 3 Align On Surface When you align a corner group on a surface all corners and edges of that group are projected onto the current surface So a corner group should be enabled active and it should contain the corners to be projected A corner group that is empty cannot be used for projection which will pop up an error message as shown in figure 4 83 Note that the corners can only be projected to the current surface 125 Figure 4 82 Before and after aligning on current surface When project on surface is clicked it pops out a dialog box asking for number of smoothing as shown in figure 4 84 A smoothing algorithm will run on the projected corners based on number of smoothings given Please select a corner group first Cancel Figure 4 83 Error message Figure 4 84 Number of smoothing dialog box 4 6 4 Align On Workplane The Align on Workplane positions the corner group to the workplane position 1 e it projects the given corner group to the workplane position Note the difference between the group fit operations and the options under the project button The group fit button deals with operations that align the workplane to the active corner group the project button deals with operations that align the active corner group to the workplane 126
107. gure 4 22 Corners linked after dragging a box around them The other ways to create edges is by checking Groups options in the link dialog box shown in figure 4 23 Keep the corners to be linked in two different groups and select those two corner group numbers Refer section 4 3 for more information on corner groups and click on Apply to link them By default the Select option is selected which enables you to simply select two corners or group corners to be linked Mode O Select Groups Select group to Select group E Cancel Apply Figure 4 23 Link dialog box with Groups mode selected NOTE Linking does not work on inactive corners 4 2 3 Insert When you create topologies for multiple surfaces nsert Shes you will often construct grid like wireframes Since adding Propagate corner layers individually for these wireframes consumes time and sacrifices precision GridPro has a feature which enables you to create quickly these often multiple corners sheet within the boundary of an already E mn All Group Edge Through existing wireframe In order to insert a sheet on an already existing Figure 4 24 Insert dialog box wireframe click on the Insert button in the Create 94 section and a dialog box opens in pop_up section as shown in figure 4 24 which asks whether single inserts are to be done or multiple automatic inserts By default Propagate method is selected which allows you to do manual inserts ba
108. has to be refined increasing the density is the tool that comes to mind first But increasing the density also affects the farfield which is not desirable So GridPro provides a tool called Enrich ai Enrich that simply adds more topology corners in a Offset length 0 02 Input corner group Select group complete topology without affecting its validity and Ok Cancel Apply without propagating to farfield This can be applied on a string of corners which will create a buffer layer Figure 4 104 Enrich dialog box around it using the offset ratio This buffer layer is nothing but a special case of internal wrap Figure 4 104 shows the dialog box of the compact enrichment You need to provide the offset ratio which gives the distance at which the internal wrapped corners should be placed By default it takes 0 02 as offset ratio The corners where the compact enrichment has to be applied have to be grouped in a group number which should be provided in the Input corner group field 4 9 Surface Assignment Utilities Unlike other grid generation programs GridPro automatically generates a multiblock grid within a region bounded by surfaces after the wireframe topology is given However to complete the topology you must tell GridPro which collection of corners are to be assigned to each surface Even if you are gridding a region bounded by only one surface you have to assign the boundary corners of your inputted wireframe to that
109. he GUI every time So all the entities you are working on UI can be switched on or off for viewing anytime from any tab from Toggle Display section located in global dock gt W Surface b Topology gt Grid gt Others Figure 2 3 Toggle Display section You can get an idea about each tool from the help button located in the bottom bar Once clicked opens a window as shown in figure 2 4 Once it is open hover the cursor on the button for which you want to view the help Load a single multiple surfaces topology wireframe undo stack grid and CAD model depending on the active panel Figure 2 4 Short help window After working on surfaces you will create topology for it which can be done in Topology tab In the topology tab in addition to corner grouping and surface grouping tools it provides you Create Edit and Assignment tools that help you to build wireframe about surfaces Lo File View Help Surface Tools Solver mS ace i Topology g Grid ie ty New Save Delete Frame Snap Pick All Current Wireframe Surface Ggrid Validity lt ER N MNOO O r E Load Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Start Stop One Has ia Hage Help rae 4ll surtaceia 0 Ifl Figure 2 5 Topology tab Once the topology building is complete grid generator is started which can be done using the icons located in global dock Next is grid visua
110. he original group With Links Links amp Projection Mo Links Figure 4 65 Copy dialog box 115 Wireframe to be copied With Links Eventhough the workplane 1S slanting With E Links option will copy the active corner group center to the workplane center k without projection No Links With Links Figure 4 66 Various copy options The other operation No Links simply duplicates the group structure on the workplane such that the center of mass of the copy of the group and the center of the workplane rectangle coincide NOTE After this action a new group is formed one comprised of the original group and it s duplicate This new group replaces the old group In order to retrieve the old group you must retrace an action in the new group by pressing the backup group button in the corner grouping wizard 116 4 4 4 Remove Remove button helps in deleting the unwanted corners from the wireframe In order to remove delete a n a ing corner switch on the Remove button in the Edit section of right side panel in topology tab and choose the mode of removal from the dialog box There are two flags available one corners which will remove both corners and the edges associated with the selected corners second edges which will remove only the Corners Edges edges and retain the corners Once the mode is selected select the corners or edges to be deleted either by picking one by one or draggi
111. hed here and the previous schedule file if any is used Also note that Ggrid cannot be restarted on a disjoint topology because a single dump file is not generated when it was started using multiple processes e Start euler There is one more option to start GGrid i e Start Euler HO which ignores the surface clustering parameters 1 e the offwall spacing of the topology Except this it behaves in the same way as the Start GGrid 42 e Restart Euler Similar to Restart Ggrid UI provides the option of Restart Euler ir which behaves same as Restart But it ignores all the clustering parameters and offwall spacing of the topology e Gridden UI also provides you the option of changing edge density while running the Ggrid You can change density and update the Ggrid engine by using Gridden option located in global dock Gridden changes the edge density dynamically e Schedule The schedule file is the file which controls the gridding process which can either be modified from UI or by editing it in notepad manually Refer section 2 3 19 for more information on modifying the schedule file from UI or refer section 4 11 to manually edit the schedule file 2 3 22 Validity Before starting Gegrid at any stage validity of topology can be checked using Validity g button Validity If the topology is valid it will pop out a message as shown in figure 2 67 If topology is invalid it will pop out a message as shown in figure 2 68 Top
112. hen the operation is ignored on those corners e Erase All the corners assigned to the current surface can be unassigned with a single click using Erase button This ensures that none of the corners are assigned to the current surface When there are no surfaces in the topology this operation is ignored This operation is internally used when a surface is deleted from the topology 4 9 4 Period As discussed in section 3 1 similar to any other surface you must assign corners to the xpolar and xyz surfaces Unlike other surfaces you have to use Period button in the assignment section Just as the periodic surface is on the periodic border of an object the corners assigned to the periodic surface is on the periodic border of the wireframe Unlike other surfaces you have to assign the corners in two steps Before start assigning the corners you have to group the corners on the periodic boundary in two different group or in same group 1 e corners represent one end of the periodic surface in one group and the corners represent the other end of the periodic surface in the second group or both the corners in the same group Then click on the Period button Pied and select all the corners which represent the one end of the periodic surface and then select the corners which represent the other end of the surface separately if it is in the same group If the corners are grouped in different groups switch on the Period button and select
113. his display mode objects on other side are visible When display modes is Points ee only the polygon vertices are displayed and all the polygon edges and faces are not drawn at all This mode is very preferable for large surfaces Similarly when working on large surfaces display mode 1 10 points can be useful It display only 1 10th of all the polygon vertices By default all surfaces are displayed as shaded The visualization for all surfaces can be changed by specifying the display type under ALL drop down menu The visualization mode of the current object surface or grid can be set independent of the remaining objects For example when all the surfaces are set to HLR mode and the current surface can be set to Shade mode it can be visualized in a better way It can be done by specifying display type for Current object under Current drop down menu The visualization mode of the moving objects while panning rotating or zooming can be set separately by specifying display type Moving drop down it defines the outlines of the object when they are moving By default the visualization mode of the moving objects is set to 1 10 points because it can be moved very easily and smoothly Display mode while moving an object should be either points or 1 10th points Under Current and Moving drop down one more option is available i e Follow all surfaces display type it copies the display type of all surfaces to current surface or while moving s
114. his end GridPro is a general purpose 3 dimensional multi block structured grid mesh generator using an advanced smoothing scheme that incorporates many automatic features 1 1 What is GridPro GridPro is an automatic object oriented multi block grid generator with a highly efficient interactive capability to build topology edit surfaces set CFD boundary conditions and view grids GridPro is unique it minimizes your work and maximizes your efficiency it is having full automation in high quality grid distribution and the book keeping of topological information Relying heavily on automation and lightly on user input GridPro generates multi block structured grids with relative ease and quickness Input the surfaces and wireframe topology GridPro does the rest Users interact with GridPro through the GUI an easy to use dynamic 3D environment that combines a powerful scripting language with a user friendly GUI front end Automated processes minimize the amount of manual manipulation required to generate a grid reducing errors in grid specification GridPro automatically creates templates of the grids to permit fast optimization to meet specific criteria To ensure that the highest quality grids are generated the software engine incorporates a unique algorithm using advanced mathematical techniques The algorithm optimizes each grid so that every element is smooth and orthogonal throughout the volumetric region under consideratio
115. ibility of properties in the 3D properties tab and vice versa 6 2 Solver Section e PDC CFA4 Below the Properties section the Solver section is located which goes hand in hand with the Properties section Firstly a CFD solver format has to FIDAP WIND STARCD be selected Various solver formats are available in the drop down of Solver menu in the menu bar as shown in figure 6 9 By default PDC format is selected FLUENT NCC CGNS DTF ACUSIM OpenFOAM sU2 Properties Property Wall Selection i Figure 6 10 Solver section Figure 6 9 List of solver formats 179 Each format has unique properties The list of property for each solver can be viewed in the field next to property in solver section Figure 6 11 provides an example of properties that are listed under property drop down list Interblk User Userl2 Periodic Userls Symmetry Userl4 Inlet Userl5 Outlet Useri Farfield Useri 7 Userg Userld User9 Userl9 Useri User20 Figure 6 11 List of properties for PDC format The Properties tab makes extensive use of skeletons for the purpose of efficient property assignment As previously mentioned skeleton of a block is the lines connecting the indexed center of the block with the centers of the block s bounding edges 2 d or faces 3 d Each block skeleton is drawn in its own color and represents the minimal amount of information required to show a broad representation of a multiblock grid
116. icking on visible surface elements will hide the selected elements This button remains depressed It need to be clicked to switch it off m button is used for Pa removing elements from current surface By clicking on m button and dragging a box using right click will hide all the elements inside the box The button will switch off once the operation is done To add elements m button can be used A box must be dragged after B ao E o E clicking on button to add elements Its behavior is similar to a Using button the selected elements of the current surface can be retained button will flip the visibility of all surface elements of the current surface All surface elements can be restored for the current surface using T button All these modifications made on Current surface can be saved using Save button Select elements a al a Figure 3 28 Curve tab for Split button 3 4 3 Refine Triangulation on the surface also plays a role in the quality of the grid because the grid points will try to position themselves on the surface nodes So when you need a fine triangulation on the surface Refine Mina button can be used instead of going back to the CAD software It is located under Edit section of the surface tab and figure 3 29 shows the Refine 74 Surface dialog box Only a current surface can be refined in the GUI so whenever you want to refine a surface select that surface as Current surface first Feature co
117. ific groups or topology or subtraction in a single operation Groups often confuse beginners because groups at first may appear to be abstract In effect the activation of a group is like the creation of an empty container This empty container discards its abstract label when you fill the container with corners and edges As already described you can add corners to groups with the el dragging the cursor over the corners that you wish to add groups 1 e you can add the corners in a group number to other group number by using the a button Similarly subtraction and intersection between groups can also be done using the respective buttons This avoids the duplication of your effort in grouping the corners again and again 4 3 2 Grouping Modes Grouping modes allow you to select the corners or edges that you would like to display while hiding the others not removing You can either view all the corners in the UI irrespective of the groups view only the corners grouped in the active group view the active group with reference to another group To achieve this GUI provides special grouping modes You can change the grouping display mode as per your requirement These grouping modes are located under A i drop down list in Groups section There are 11 group display modes available as shown in figure 4 53 Each letter represents a topology mode one that controls how active groups are distinguished from inactive groups You can select
118. ilities Merge Move Copy and Remove are the four buttons located under Edit section that can be classified under Topology Modifying Utilities In addition to this Face Exclusion utility is also included under this section Figure 4 59 Edit section 4 4 1 Merge Merge can be done for two corners or two sheets of corners Sometimes you would like to merge two different wireframe of similar pattern with same J To number of corners into one Merge can be done in two ways by dragging box around the corners using mouse right click 1 e Screen Select or placing corners into a ae ae different corner groups and selecting the respective groups 1 e Group Figure 4 60 Screen select tab dialog box 112 Screen select tab provides you three options to position the selected corners after merge as shown in figure 4 60 First is To Center option that will position the merged corners to the center of the input corners Second is To Selection 1 option that will position the merged corners to the first selected corners position Similarly To Selection 2 will position the merged corners to the second selected corners After selecting the position where corners need to be placed after merging select the corners using mouse right click A corner or sheet of corners can be selected A single drag box will work if two separate sheets of corners are used but you need to drag two boxes separately when the sheets of corners are linked to each other
119. ill appear whenever the user try to do trimming operations on the blocks If add or subtract or intersection in Trim Blocks operation is selected the skeleton will appear in addition to the outline Once trimming blocks operations is done the skeleton will disappear All the operations under Trim gt Blocks deals with activating and deactivating blocks In order to deactivate a block deactivate the skeletal center of the block By default all the blocks will be on If the block s center is deactivated the outline of the block will not be shown Visually the cut out blocks will allow the user to view the inside region of 3 dimensional the grids as solid objects or to view slices of the grid which do not propagate beyond the active blocks If a block skeletal center is a filled colored square the center is activated If a center is a hollow colored square the center is deactivated The Mesh button places a mesh on the exterior boundaries of the activate blocks The result of pressing Mesh is the display of the active blocks as if they were a solid object The propagation is limited to the active blocks 170 e a ELAS A Ly S ZS 2 X Pa Y XPD S62 Figure 5 28 Trimmed blocks and trimmed blocks with grid cells Because most grids will contain numerous blocks user will often need to activate or deactivate many blocks at a time If block by block activation or deactivation is required
120. ing on is called current grid In the Delete option in Grid tab the Current grid operation deletes the current grid and the All grids operation deletes all the grids in the Grid tab Similar to the topological entities corners and edges grid also has sheets as an entity that can be manipulated All sheets can be deleted using Delete All sheets in Grid tab You can hide the unwanted sheets in Grid tab to avoid clutter and hidden sheets can be deleted using Delete Inactive sheets in Grid tab Current grid All grids Inactive sheets All sheets Figure 2 39 Delete drop down list in Grid tab 2 3 5 Undo Redo When you input corners and edges in the GUI you will often make mistakes GridPro remembers every topological operation you perform and enables you to go back and scroll through ir every operation using Undo button 4 in global dock Therefore you can erase all topology you C have created from any point in the process Also you can scroll forward using Redo button if you realize that you should not change anything Both the buttons are disabled in all other tabs except topology tab because you cannot undo any other surface grid properties related modifications However adding and deleting surfaces can be undone using the undo button in the topology tab 2 3 6 Frame When you are maneuvering any object in the UI it tends to happen that you moved away really far or you zoomed in too much or you zoomed out beyon
121. inked to the original string such that no links intersect one another Because wrapping strings or faces of topology is common and can be a laborious process GridPro has developed a feature that allows you to create a wrap automatically using groups Since you must place a wrap around every curved boundary as well as most boundary angles you will more likely be wrapping wireframe than not Before you learn how to wrap you must first learn what to wrap On a plane a closed or open string of segments is wrap able Each corner in the string must be the endpoint of one or two edges not three or more edges All edges must be part of the same string and no more than two corners can define an edge There is no restriction on the direction of the string or of the angles formed from connected edges In space a closed or open string of quadrilaterals is wrap able Each connected edge in the string must be common to one or two quadrilaterals not common to three or more quadrilaterals All quads must be part of the same string Sometimes you may want to exclude a face of a wireframe in order to achieve a certain wrap Excluded faces contain a diagonal represented by a dashed red line these faces are ignored by GridPro during the wrapping process Thus a string of one dimensional segments which form a rectangle could be considered as a two dimensional quad if the face is not excluded If you depress the F key and click two opposite corners of a fac
122. ion inserts the multiple sheets based on the number inputted in the Multi Insert dialog box as shown in figure 4 32 97 Figure 4 33 After Multi insert 4 2 4 Macro Macros are pre assigned topologies which can be often used for simple geometry creations and to create the outer domain Therefore the software offers some topological templates from which you can input objects such as surfaces and or wireframe Macro button is located in Create section of the right side panel in Topology tab Similar to built in surfaces macro has different options for 2D and 3D In case of 3D box ellipsoid and cylinder macro are available as shown in figure 4 34 andin case of 2D rectangle circle and ellipse macro are available as shown in figure 4 35 Both for 2D and 3D you can load a user defined topology Depending on the dimension of the workspace chosen the corresponding macro is enabled i e if the workspace is opened as 3D 3D macro buttons are enabled 1f a 2D workspace is opened 2D macro buttons are enabled The dialog box of each macro allows you to choose the surface and or wireframe you would like to create Each option has its own macro dialog box which is located in right hand side panel Rectangle E3 EJ Wireframe Surface Topology Resize Default Size axis Resize Default Size X axis Y axis Z axis Min value 1 i Max value 1 Min value Max value Ok Cance
123. ion to predefined templates a user defined topology can be loaded into current graphic window You can load either 2D or 3D user defined topology respective to the modes 2D or 3D using Load gt Template yy option Load Topology Template dialog box will pop out as shown in figure 2 31 if Load gt Template is selected Select the file you would like to input by pressing Select file push button You can load a particular corner group from the chosen file if you want Similarly you can also load a particular surface group from the chosen file You can change the position of the loaded topology by using the transformation options The Load Template options are available solely to maximize your efficient use of GridPro It acts as a template for the geometry of similar shapes It s mainly helpful while doing design optimization where you modify the surfaces every now and then to get an optimum shape in such cases building wireframe for every modification becomes a painful and time consuming process It helps in loading the previously used wireframe and modifies it according to the surface modification File name Corner group Selectgqroup Surface group Select group Translation 1 0 0 0 0 Scale 1 0 Rotation axis 1 0 Rotation angle 0 0 Translation 2 0 0 Cancel Figure 2 30 Load Topology Template dialog box While you are working on any topology in GUI it saves your topology by default every 2 minutes with _auto f
124. ipse dialog box Similar to other surfaces the workplane data can also be used to create the ellipse surface by clicking on the Get workplane parameters The center of the workplane is copied to the center field of the ellipse The workplane length along workplane x axis is copied to major axis 63 radius field The workplane width along workplane y axis is copied to minor axis radius field If both the axes are perpendicular to each other and the radii are equal the ellipse is equivalent to a circle 3 1 3 Explicit surfaces GridPro can create few explicit surfaces also Explicit surfaces which can be readily used in GridPro are in quad tria tube or lin format Except for tria triangular other three can be created using the options available under Surface Tools located in the top menu bar e Tube A tube can be defined by the revolution around a center curve The revolution for each point on the center curve is performed in the normal plane of that point with respect to the tangent of the curve Hence a tube is represented by a set of points on the curved center line or axis and a variable constant radii at all the cross sections of the tube Surface creation tools are discussed in section 4 10 e Quad Another 3D explicit surface that can be created in GUI 1s quad surface A quad surface is composed of unstructured quadrilateral elements 4 points define each guad element The quad files in GridPro is represented by quad as an e
125. itself Instead GridPro will display the progress in the console window that will dynamically give information about your run The numbers displayed in the console window convey information about the quality and convergence of the grid being processed The first three letters shown swp form an abbreviation for sweep The number proceeding sweep illustrates the number of times GridPro has visited your topology in its attempt to optimize the grid in the corresponding region Every subsequent sweep relies on information processed in previous sweeps in order to improve the quality of the grid In other words the more sweeps you allow GridPro to perform the better your resulting grid In order to numerically measure convergence for the grid optimization process look at the residual number found in the status window This number follows the r expression found in every sweep and indicates the disparity between the actual grid and an ideal grid An ideal one would require a limitation on generality and an infinite number of points Because this ideal is unobtainable GridPro compromises by creating the best possible grid for the chosen topology a grid that is consistent with the number of points and specified parameters of the topology As the grid generation process converges the grid s residual number becomes constant As the number of sweeps increase the residual number will often oscillate and then converge to a constant Often however the residual
126. ity The density of a grid is of great importance a grid can be used for analysis only if the gridded region is sufficiently resolved Before you begin the gridding process you can specify the density of the grid you wish to create Density is a number that describes the number of grid cells along an edge and thus all compatible edges The grid cell count is directly proportional to the grid s overall density Including both endpoints of an edge the number of mesh lines present is one more than the number of cells inputted You must set the density of the grid in the Topology tab you will not see the results of any density alterations until you actually see the grid in the Grid tab By accessing the density Best button under Edit section in Topology tab you can alter the grid density of sets of topologically parallel edges or all edges You cannot alter the density of only one edge or a pair of topologically perpendicular edges Clicking on the density button opens a dialog box as shown in figure 4 94 where you can change the density of all the edges 133 Global density 8 New value 8 Cancel Figure 4 94 Global density dialog box The Global density field displays the current density of all edges and the New value field displays the new density of all the edges By default both the tab shows 8 always that will change once it is modified If you wish to alter the density of a set of topologically parallel edges firs
127. ize it as such Unlike other grid generation programs GridPro does not require you to identify a geometrical object after you create it GridPro will read only topologies containing full face matching These topologies include intersecting quads with intersecting faces having the same dimensions or intersecting 84 hexes with intersecting faces having the same dimensions In other words one side of one quad cannot intersect one side of two other quads and one face of one hex cannot intersect one side of two other hexes correct topology incorrect topology incorrect topology concave quadrilateral Figure 4 1 Topology examples Now that you know the topological form expected from GridPro you should make sure that you understand how to decompose a region and create a topology Because surfaces can be complex they may require complex topologies Unfortunately no set of rules can define how all topologies could be constructed There are some rules however which define how most topologies should be constructed when there is no other special feature or concern When you create topologies about angles in surfaces you should consider the concavity or convexity of the angle This is seen from the viewpoint of the region to be gridded rather than from outside that region looking inward In the following examples the dashed structures represent surfaces and the solid structures represent a possible correct topology for those surfaces
128. l 1 10th of original points When an object is set to Shade with HLR re Figure 2 51 Different display modes visualization mode the polygon faces of the object are drawn using the object s own color but the polygon boundaries edges are drawn in white Figure 2 52 shows a surface in this visualization mode Note that since the polygon faces are drawn and are opaque the objects on the other side of object cannot be seen RIFET TN T F ATED a wE a E RAS LOBES ie a Ke PT 7 Lo 1s Gh mn UES ER RA gt 75 v Ce ae Wat ar egna ss 3 NAA Ul tat aT ata ee Eri eae s A A ETa FR CHH w L j FENN 1 ra maa Tsar Ay oy oe te ies ee Ne as ey Shade with ae P 7 i 1 10th of original Figure 2 52 Surface with different display modes 35 In Shade B isualization mode the polygon faces of the object are drawn using object s own color The polygon boundaries edges are not drawn at all The objects on the other side of object cannot be seen because of opacity In HLR Hidden Line Removal visualization mode the polygon faces of the object are drawn using the background color and the polygon boundaries edges are drawn using object s own color Note that the objects on the other side of object cannot be seen When display mode is set to Lines pp the polygon faces of the object are not drawn and the polygon boundaries edges are drawn using object s own color In t
129. l Apply Ok Figure 4 34 3D Macro options Figure 4 35 2D Macro options 98 e Box When Macro button is clicked by default Box macro dialog box opens as shown in figure 4 34 if it s a 3D workspace The box macro Fit active surfaces allows you to create automatically a three dimensional region bounded by 6 Fit current surface planes You can create only surfaces or only wireframe or both 1 e topology curr surf group by selecting the one of the options in pop up By default Topology is an oe selected which provides a wireframe box structure and six planes along Last setting with respective corners assigned to its respective surfaces The wireframe Enlarge 100 option creates only the wireframe and the surface option creates only the Enlarge 10 Enlarge 1 Reduce 1 Reduce 10 Reduce 50 Fig 4 36 Resize drop down list surfaces The Resize drop down list allows you to resize and or fit your surface and or wireframe accordingly Figure 4 36 shows the list of options in the resize drop down This resize option automatically fills up the dimensions fields in the dialog box of respective macros The default option allows you to manually input the values in the below fields for the given macro option The fit active surfaces option calculates the minimum and maximum boundary of the active surfaces in the GUI along all three axes and update it in the below value fields whereas the fit current surface option uses only the curr
130. ld then create an inner layer between the smooth surface and decomposed block The inner layer is illustrated in dark shade Figure 4 7 illustrates a correct topology for a smooth surface Figure 4 7 Topology for a smooth surface Notice how the darkened lines follow the path of the circular region In figure 4 7 the topology conforms well to the corresponding geometry Also this example shows how topology is wrapped around the continuously curved portion of the surface The figure formed by the dark lines is considered a partial wrap Looking at the angle variations above you will notice that the angles close to 180 degrees are wraps In fact at every point of a smoothly varying surface the angle is computed from the corresponding surface tangent line Look back at how topologies are created for angles between 90 and 360 degrees Notice that some of those topological configurations are wraps as well In figure 4 8 the partial wraps formed for the continuously curved surfaces are illustrated in dark shade 87 2Beeeereeeeaeeeeae amp i a B i i a a A e nm Pe 6 4 8 i 8 po o o ootd A 6 8 i 6 be e eoeooeoroaoe eeorsoaaedea E Figure 4 8 Topology for continuous curves Notice that in the above example wraps are formed around the 270 degree angles as well Figure 4 9 displays the full wraps in dark shade i i E a j yA i 4 a I i I i
131. licked edges are also created between the newly formed corners If the Group mode is used and a group is not activated the mode functions similar to All mode The other way to do an insert on an edge is based on the density Switch the Insert tab from Propagation to Density based as shown in figure 4 28 With the help of this density based tab you can either do the multiple inserts on all the edges or only to the edges which are grouped in the current group Every edge has a default density of 8 which is called as base density Based on the base density you provide it will determine the number of inserts So the given base density should always be less than the default density in order to calculate the number of inserts You can also use this option on selected corners by keeping them in a corner group and input the corner group in the fields provided If no corner group is selected it will consider the entire topology Density Based Base Density 8 Corner group Select group Allow internal wrap Cancel Apply Figure 4 28 Density based dialog box Note Similar to Link Insert works only for active corner group The insert propagation is based on selected propagation method Edge info ry Center of rotation S Insert Sheet S Insert Block S Multi insert Change density Figure 4 29 Right click menu of edge In addition to the Insert button in the Create section you can also insert using the right click
132. lization which is done in Grid tab The Grid tab provides you the tool to View the grid Edit the grid and check the Quality of the grid mm File View Help Surface Tools Solver a A HAS Q T ea ag Save Delete Frame Snap Pick All Current Wireframe Surface Ggrid Validity Soo Qaga2grrsreaevpeeses Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Start Stop ee urtace ia 0 zhi eset Sae gt He Figure 2 6 Grid tab The fourth tab is Property tab which allows you to assign properties to the grid The tools in right side panel allows you to assign properties to grids All these tools will be discussed separately in the following sections lt File View Help Surface Tools Solver 2 iti Topolog Grid i Property g t F A ay R e os T Y V p ZA Z 2D Properties New Save Delete Frame Snap Pick All Current Wireframe Surface Ggrid Validity D Sheets cs Ha Kae kw eo E Load Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Start Stop be X S aa S Fit3 Property Wall Properties N a Selection b r ponn pn Fix Aap _ Center Fill Section Handle L Help Num Cells 0 lt surtace ah zhi apelata Figure 2 7 Property tab 2 2 Top Menu Bar The top menu bar of the GUI consists of five menus such as File menu View menu Help menu Surface Tools and Solver All the menus ar
133. ll display the skeletons of all faces which do not contain the current property and allows the user to assign the current property to many faces by dragging a red box with the right mouse button over their skeletons centers Depressing the nia button will display the skeletons of all faces which contain the current property and allows the user to un assign the current property from many faces by dragging a red box over their skeletons centers Once the property is unassigned from the faces the un assigned faces will be automatically added to the wall property When one button is depressed the others un depress The process of assigning properties to blocks is identical to that of assigning properties to faces Here the 2D properties tab has to be switched to 3D Properties tab The chosen property format determines the list of 3d properties to be displayed when the drop down next to properties in solver section is clicked Figure 6 13 3D Property list of PDC format 181
134. lso hidden The indices of the corners can also be toggled separately using the check box of corner ids The highlighted edges and face diagonals can be shown hidden using the option toggle error d Topology Wireframe Corner ids Error Figure 2 81 Topology sub menu 52 Topology errors are automatically detected and highlighted in red when you try to launch an incomplete fra file The error and highlight display points precisely to the problem area that prevents Ggrid from running To remove this highlight uncheck Error under Topology section in Toggle display section Errors are displayed only when you attempt to start the gridding process of an incorrect topology e Grid By default grid is only displayed in Grid and Property tab where it is viewed and analyzed Sometimes you may want to hide show grid and its entities Unchecking the Grid check box can hide the grid checking it back can show the same Similarly the blocks of the grid can be toggled by checking box next to Blocks under Grid branch Similar to surfaces each block is given an unique number called block id and each block has unique IJK positioning in order to see the IJK axes for each activated block check the block orientation under grid branch in toggle display panel The IJK axes will appear near the center of each block When the grid blocks are hidden their id s and their orientation are also hidden To show hide the block indices use the check box of block
135. ly runs the connectivity file when you access blk tmp 154 CHAPTER 5 GRID Grid visualization is carried out in Grid tab Once the Ggrid is run and grid is generated you would like to check the grid In the Grid tab you will find grid viewing utilities preprocessing utilities post processing utilities grid probing utilities grid quality check utilities and tools to toggle grid amp grid sheets All these utilities are placed under 2 sections namely Grid toggling and Tools section at the right side panel of Grid tab Once grid is generated you can load a blk tmp default name saved by Ggrid file from the working directory Any number of grids can be loaded in the Grid tab at a time You can work independently on each grid UI allows you to use the tools on different grid without affecting other grid in the UL A grid can be split up sliced and represented in many different ways The block traces composing a grid contain edge outlines centers of mass and skeletons links from the center of mass to the center of each face These various features can be hidden or activated in various ways in order to display different parts of a grid are located in Grid tab 155 5 1 Grid Viewing Utilities Because meshes are used extensively for analysis testing GridPro allows you to visualize them in different ways First and foremost in order to understand meshes you must understand the difference between blocks faces slices sheets and
136. mber separated by a space which represents the coordinates of x y and Zz axis for the corresponding input Center Axis 1 Axis 2 Axis 3 Radius Power Get workplane parameters Cancel Apply Figure 3 5 Ellipsoid dialog box Similar to cylinder the workplane data can also be used to create the ellipsoid surface by clicking on the Get workplane parameters The center of the workplane is copied to the center field center of the ellipsoid The workplane X Y and Z axis orientations are used as the axes of the ellipse and the workplane length width and the diagonal length are copied to the radius fields of X Y and Z respectively The powerof the ellipse is remain unaltered when the workplane data is used 59 e Symmetrical surfaces Some geometries are translational symmetric or rotational symmetric Rather than computing the whole grid about such an object at once GridPro can grid a section of the object then duplicate that section to construct easily the grid about the whole object This process saves time and effort and allows to construct topology for only a fraction of the region that needs to be gridded The required section of symmetric objects is created with periodic surfaces called Xpolar and XYZ The Xpolar surface is used for rotationally symmetric geometries and the XYZ surface is used for translational symmetric geometries These surfaces comprise nothing more than the periodic bor
137. metry Grid STEP IGES STL NASTRAN COUAD NASTRAN CTRIA NASTRAN to GridPro HEXA NASTRAN to GridPro MIXED PATRAN STARCD Plot3d Fluent Figure 2 16 Import formats of geometry and grid Upon selecting the formats it opens a file dialog box in the working directory from which you can select the file name to be imported The file dialog box would be filtered automatically for the selected file format Export option allows you to export various surface and grid formats from GridPro Once the appropriate format is selected it converts the file from GridPro format to the selected output format and saves it in the working directory Figure 2 17 shows various export surface and grid formats available in the UI 17 x Surface Grid GridPro tria FATRAN NASTRAN STL tria GridPro quad tria with norm vector field NASTRAN PATRAN CGNS OpenFOAM 5U2 FLUENT Acusim CFX4 Starc D Plot3d DTF GASP FIDAP GridPro Superblock Figure 2 17 Export formats of surface and grid The Quit option defined under File menu can be used to quit the application A confirmation dialog box as shown in figure 2 18 is popped up to ensure that it is not closed accidentally The user has to make sure that all the modified data is saved before the application is terminated Are you sure you want to quit GridProa Figure 2 18 Quit confirmation dialog box 22 2 View menu The View menu contains options t
138. n GridPro runs on all major Figure 1 1 Missile configuration operating systems and hardware The design of GridPro has followed the principles 1 Minimizing the user input with a strong emphasis on topological template construction capability and reusability 2 Maximizing the grid quality 3 Optimizing the grid distribution The first principle cuts down both the initial setup time and more drastically the subsequent setup time for configuration modifications the second translates into a higher solution accuracy and faster convergence for the CFD solvers and the third reduces the demand for computer resources in terms of both the CPU time and the amount of RAM usage The mathematical underpinnings that reduce the user effort also account for GridPro s substantially high grid quality This quality comes in the form of near orthogonality smoothness low warpage and curvature clustering for both concave and convex boundaries GridPro can be used for multiple applications in multiple ways The program will grid simple cases or complex cases in two or three dimensions By producing grids on objects as diverse as a nuclear test missile or a brain aneurysm GridPro showcases its flexibility as well as its depth Obtaining realistic configurations is an essential industrial need for engineering Figure 1 2 Brain aneurysm analysis These configurations are often complex and normally require a large amount of human time t
139. nar then the axis should not be 149 perpendicular to this plane Orientation value combination gives the same output as cylinder option so cylinder is recommended to use for this combinations The file name for the resultant tube surface can be provided using the push button provided below the axis and radius fields A file selection dialog box is popped up to input the file name to save the output surface Give the desired name for the tube surface file with which you want to save The tube surface can be smoothed using the approximation scheme which can be enabled by checking the check box next to the smoothen tube If the smoothen tube is enabled then the number of levels of refinements need to be selected from the drop down list provided next to the refinements This drop down is disabled until smoothen tube is checked Sometimes it is desirable to have the tube surface closed on both the ends this can be achieved by checking the check box add caps It will add caps to both sides Note that the radius of the last point on the cap of the tube surface should be zero But a tube surface by definition cannot have zero radius at any cross section Hence a very small radius of le 5 is used at the end of the cap resulting in a small hole However this hole will not affect the quality of the grid 4 10 8 Internal surface Internal surface is another tool which creates a quad surface using the corners created at the intersection of s
140. nder surface by clicking on the Get workplane parameters The center of the workplane is copied to the center field of the cylinder The workplane X axis and Y axis orientations are used as the major and minor axis of the cylinder and the workplane length amp width are copied to the radius fields The Z axis of the workplane is used as the direction along the length of the cylinder The power of the ellipse and length of the cylinder is remain unaltered when the workplane data is used 58 NOTE The power option defines the relation that provide the shape of the built in surface An ellipsoid includes cylinder circle ellipse is defined by a second order function which render a shape of an oval A superellipsoid is defined by a higher order function For a power equal to 2 according to the ellipse equation a circle would be formed if power is more than 2 a super ellipsoid is formed which looks more like rectangular prism e Ellipsoid An ellipsoid is defined by the center three axes their radii and the power of the ellipsoid In order to input an ellipsoid click on the ellipsoid button Fllipscidin the Create section Figure 3 5 shows the ellipsoid dialog box of the ellipsoid button which appears on the right side panel The radius and power field require a single real positive number which represents the radius on all three axis and power determines the shape of the ellipsoid The center and axis fields require three real nu
141. ndition is you must also have grid connectivity file conn along with grid Once the button is clicked a confirmation dialog box pops out where you need to click on Ok to confirm the execution of the process 160 BOOS Ea Et fe Ed Figure 5 13 Location of the Extract 5 3 Post Processing Utilities Sometimes user might like to make some minor modifications in the grid say changing density in few edges GridPro post processing utilities are used once the grid is generated There are two post processing utilities Density and Mirror 5 3 1 Density Similar to changing the number of cells for particular parallel edges or whole topology HE before a grid is generated user can also change it after a grid is generated using Density button in the Tools section in the right side panel under Grid tab It is a post processing tool the changes done are limited to grid file only and it is not updated in topology file Block index Axis x Current density 9 New density 18 Output file outgrd Cancel Apply Figure 5 14 Density dialog box Density button has four tabs each performs different operations as follows Once you click on the Density button Change grid Density dialog box opens as shown in figure 5 14 By default the tab is set to Edge The density of a particular edge group can be changed using Edge tab An 161 edge has to be selected for which the density has to be changed Enter the new de
142. ng a region to be gridded can also be imported It also has a certain capability of automatic surface restructuring and repair such as auto stitching of surface gaps between surface patches and implicit surface trimming and intersection capturing First step in gridding process is to define the region to be gridded as shown in figure 1 3 After inputting surfaces whether or not they are built in from GridPro or from CAD a topology for the region bounded by those surfaces has to be created The majority of GridPro operations deal with creating and modifying topology GridPro s unique methodology significantly increases productivity by minimizing the amount of user interaction and individual input It partially automates topology generation by reducing the user task to generate a coarse wireframe of the topology in which only imprecise corner and edge information is required while the blocks and block faces are automatically generated from the wireframe Topology generation contains two parts a wireframe construction and b surface assignments A topological framework or wireframe topology see figure 1 4 is properly designed according to the multi block scheme GridPro utilizes Upon inspection user can note that the wireframe defines a pattern of grid points To design a wireframe correctly first define the wireframe through the creation of a coarse unstructured quadrilateral 2D or hexahedral 3D grid about the region U
143. ng a box around it If the corners mode is selected and you drag Figure 4 67 Remove dialog box a box around a bunch of corners all the corners within the selected box will be deleted along with the corresponding edges If the edges mode is selected only the edges within the selected box will be deleted and the corners will be retained in the same place GridPro offers shortcut key for most frequently used operations Hold the R key on the keyboard and select the corners to be deleted If you want to remove an edge Hold the lt R gt key or switch on the remove button and click on the edge to be deleted The cursor will become a two sided vertical arrow when you move over an edge Note Remove operation does not work on inactive corner groups There is another operation which is also embedded with remove button 1 e Faces Faces removes a sheet of corners if its pattern replicates the adjacent sheets It is the cannot uninsert corners in the group reverse of insert where it inserts a sheet similar to adjacent sheets But Faces remove the sheets if it is similar to the adjacent sheets It is helpful in removing the extra blocks in order to reduce the total number of blocks Figure 4 68 Error message in the wireframe In order to remove a sheet group the corners of the sheet in a group number then click on the Remove button and click on the Faces option in the remove dialog box The corner group should be active in order to execu
144. ng buttons works for grid sheets just like how it works for the blocks when the trim mode is set to Blocks Before the buttons in the Sheets tab are used however a grid sheet must have already created the buttons in the Sheets tab can manipulate only the faces a oo on the current grid sheet Similar to the button for trimming blocks one by one the ii button will allow the user to trim the faces of each blocks one by one by picking the face centers of the given sheets The other buttons are the same and works the same way for the sheet faces instead of blocks depends on the mode set in the trim section Li tT TO ae oe ee ee a a A le e on oo oe oe ay a he a Htagraari sci s i an e EEEE sheet Figure 5 32 After trimming two faces of the grid 173 Figure 5 31 Skeleton for the grid sheet CHAPTER 6 PROPERTIES Before exporting grids for CFD solvers you may want to set properties boundary conditions on these grids You can set properties in two different ways either set it on the surface which will be reflected in the grid or directly on the grid once it is generated GridPro enables you to set two dimensional and three dimensional properties That 1s you can assign properties to each face of each grid block and to the volume of each grid block itself You set properties in the Properties tab Figure 6 1 illustrates the operations associated with the Properties tab Property tab allows you to assign diffe
145. ng out an assigned corner for an external surface or 3 edges emerging out for an internal surface in 2D 1s called very severe singularity 131 Figure 4 92 Very severe topology NOTE The above explanation is not applicable to the corners which are at the surface intersection In other words it is not applicable to the corners which are having more than one surface assignments 4 7 1 Heal All these singularities can be either solved manually or automatically using Heal button located under Edit section Figure 4 93 shows the Autofix singularities dialog box All three can be solved using a single dialog box in a single operation The mediumly and very severe singularities are solved by doing a wrap either internally or externally while the mildly severe singularity is solved using an internal surface These internal surfaces have to be replaced with the user created internal surfaces as these surfaces cannot be used for generating the grid The mildly severe can also be solved in two other ways by giving overlapping assignments and using surface by surface wrap Retain corner group Select group Y Concave corner group Select group Y Eliminate Very severe singularities Eliminate Mediumly severe singularities _ Eliminate Mildly severe singularities Ensure buffer layer Offset length Cancel Figure 4 93 Heal dialog box 132 The first field is retain corner group which contains the corners whose singularity has to be
146. ng the 8 key in addition to picking corner one by one you can also drag a box with right click mouse button around a group of corners Note that these shortcuts can be modified using the keyboard settings described in section 2 2 4 9 3 Erase There are two ways to erase or unassign corners A dialog box as shown in figure 4 107 once the Erase button is clicked Select lets you unassign multiple corners that are selected by dragging the mouse While Clear removes all assignments for current surface 142 e Select To unassign multiple corners to the current surface simultaneously use Select button under Erase When Select button is active user can drag a box by pressing the mouse right click button to select the corners from the graphics window The selected corners which are assigned to the current surface are unassigned Note that only the corners appended to the current corner group are eligible for selection If none of the corner groups are active all the corners of the topology are Figure 4 107 Erase dialog box eligible for selection Also note that if there are no surfaces in the topology this operation is ignored This operation can also be achieved using the shortcut Shift S key By holding the shiftt s key in addition to picking corner one by one you can also a drag a box with the right click mouse button around a group of corners If the corners are assigned it becomes unassigned if it is not assigned t
147. nlike the frames of some other grid generation systems the pattern defining points do not need to be precisely positioned Figure 1 4 Wireframe for the region enclosed by the surfaces in figure 1 3 The two functions which help in building wireframe or can be said as heart of creating topology are groups and the workplane Firstly the workplane is a tool which guides the cursor in three dimensional UI The workplane is simply a plane in space that is used for interactive topology generation and for graphical viewing Second the groups are the most sophisticated tool to use while working on the complex geometries Groups are simply collections of or set of 4 selected corners and edges Groups allow the user to create topologies many times faster than sequential corner by corner edge by edge constructions on the workplane These are the two functions helps the user to generate topology effectively and efficiently Apart from these tools there is an important term which will be often used in the manual 1 e the current surface The current surface is a surface on which the function can be executed or applied The current surface can be identified in two ways one depends on the color of the surface it is always highlighted in sea blue color second method is using the surface id which is displayed in the GUI which will be discussed later After completing the wireframe an association between wireframe and surfaces is requir
148. nsity for the selected edge and click on Apply to see the changes When the Apply button is clicked a new grid file is created with the name specified in the Output file input field and automatically loaded into the UI Once the new grid is loaded the old grid will be switched off which can be switched on again from the Grid Toggling section The density of an edge of a block can also be changed by using Change density option from right click menu Selecting Change density option from the right click menu of a grid block edge will open the same dialog box as shown in figure 5 14 The second tab in Density dialog box is Matching whose dialog box is shown in figure 5 15 A particular density of a whole grid can also be modified using this option It will modify the density of the edges which were having the edge density as mentioned in the existing density field Input both the existing and new density along with the output file name in the corresponding fields and Apply to see the changes All the edges which have the density as mentioned in the Existing density field would be replaced with the New density value A new grid will be created and loaded into the UI Once the new grid is loaded the old grid will be switched off which can be switched on again from the Grid Toggling section Existing density New density 18 Output file out grd Cancel Apply Figure 5 15 Matching tab dialog box If the density of the whole grid has to
149. ntities by using Probe button Pree located in global dock When you click on it the mouse changes to the object selection mode and you can click on corner edge surface of the topology or grid sheets block edges of the grids in the graphics window The information regarding the selected object is displayed in a dialog box which is popped up after the selection When this button 1s clicked it is pressed down till the selection of an object from the graphics When a corner is selected the corner data is shown in the tabular form as shown in the figure 2 46 The corner index it s position vector the list of corners linked to it the surfaces to which it is assigned and the corner to which it is paired 1f the topology is periodic are all listed in the table Note that this information can also be obtained from the topology fra file Corner td l l Coordinates 1 000000 1 000000 1 000000 Corner id Coordinates 4 1 000000 1 000000 1 000000 2 1 000000 1 000000 1 000000 Linked Corners T 1 000000 1 000000 1 000000 Surface id type plane Built in Surface Assigns a plane Built in plane Built in Paired Corner None Figure 2 46 Corner information When an edge is selected the edge data is displayed in a dialog box as shown in the figure 2 47 The edge index its end vertices its length and the density of the edge are all displayed in the dialog box The length of the edge is the distance between its
150. o produce a grid GridPro s automated process handles massive complexity that requires a large number of blocks very efficiently with a large number of blocks It can take hundreds or thousands of blocks There is basically no limit in number of blocks 1 2 How GridPro Works GridPro is automatic grid generator which accesses an automatic process earlier than any other automatic grid generator Included in GridPro s automation are such tasks as surface grid generation zone construction and the intersection between surfaces GridPro essentially reduces grid generation to topology generation The primary user input is a pattern of points referred to as the grid topology The language that organizes this pattern of points is called Topology Input Language TIL You can input these points directly in the GUI As you input points in GUI TIL code is automatically generated Users have choices of using GUI and or TIL code The grid generation process in GridPro is primarily consists of four sequential process they are Surface preparation Topology generation Grid generation oe 1 Property setting GridPro contains built in surfaces which are ellipsoids and planes that although simple are helpful in many practical circumstances However because real life objects rarely mimic symmetrical regions surfaces from other design programs such as CAD Computer Aided Design Figure 1 3 A collection of surfaces boundi
151. o real numbers separated by a white space representing the center of the circle and the radius and power field require a single positive real number representing the radius of the circle and the shape of the circle As discussed earlier Refer cylinder if the power is more than 2 the shape would look more like a rectangle 62 Specity Size Center Radius Power Get workplane parameters Cancel Apply Figure 3 10 Circle dialog box The workplane data can also be used to create the circle surface by clicking on the Get workplane parameters The center of the workplane is copied to the center field of the circle The workplane diagonal length is copied to the radius of the circle e Ellipse Ellipse is similar to ellipsoid in 3D It is defined by its center major and minor axis and oe radius along respective axis and the power of the elliptic surface Clicking on Ellipse button Elirse in 2D tab of Create section opens Create Ellipse dialog box as shown in figure 3 11 As discussed earlier the center the major axis and the minor axis fields require two real numbers each representing the x and y coordinates components separated by white space and the radius amp the power requires a single positive real number representing the radius along the X and Y axis and the shape of the ellipse Specify Size Center Axis 1 Axis 2 Radius Power Get workplane parameters Cancel Apply Figure 3 11 Ell
152. o toggle the toolbars and the view screen mode as shown in figure 2 19 18 Tal Maximize Status bar Windows Dockwidgets Figure 2 19 View Menu bar To view the entire screen in Full screen mode select Fullscreen option under view menu as shown in figure 2 19 The full screen mode is shown in figure 2 20 This hides the desktop panel system tray and all other visible applications but the top dock left side tool bar and the right side panels are remain unhidden To bring it back to the default size click on the maximize option which retrieves the default screen size File View Help Surface Tools Solver me I Topology zi EA N Y ia A Bak BAW eO 2 Bey New Save Delete Frame Snap Pick All Current Wireframe Surface Ggrid Validity aor ages do oa TOG be Load Undo Redo Zoom Unzoom Probe Select Display Woikpiane Grid Stop jeje periti Uire Show short help ta apa al surtaceia 0 Ii E Figure 2 20 GUI in full screen mode The bottom Status bar that displays the information related to each icon and the status of each operation can be toggled off for display by unchecking the Status bar under View Menu 19 Similar to Status bar right side panel left side toolbar and top dock can be switched off for display using options defined under Dockwidgets in View menu as shown in figure 2 21 You can switch off all at a time or you can manually switch off one at a time based upon your neces
153. oe E o gt D na S DF e sig els amp 8 amp 278 ORG QM wo SF BF al a S as o D ooog p z AO ON O S g gt O Oy S Si oO 2 O T O o 8 TT A ee nm J fe oOo V0 S o a o aBa o a em SZ SAO D Oo OB o O S V y 1 Paes ees egae gsy FRERET AR ET og orgoog L z C85 076 25657 a rT f gi A3 Ry k T Z me mi E Dy a Oo O o v O G efi Qi Ws Ge Dm Ge HE we 2 9 SSSED O A cE 3 HE Ss22eesfsow 167 Global dock As discussed before current grid can be deleted using Current grid option under Delete button in Global dock Below the grid names list there are five buttons placed as shown in the figure 5 24 The First two buttons are enabled for only Grid slices The rest three are enabled for all the three tabs With respect to Grids tab the third button i e Show all Grids ey button switches on the display for all the grids loaded into GUI The fourth button 1 e Show only Current Grid button hides all the other grid and displays only the current grid The fifth button i e Toggle all grids button flips the display of the grids in the GUI 1 e Grids which are displayed will be hidden and grids which were hidden will be visible Once the Current grid is selected user can create as many grid sheets as he wants The grid sheets can be Slices toggled from grid Slices tab It will show only the sheets belonging to the current grid Similar to grid tab grid slices have the same options A sheet can be selected as
154. of its dimension 2D or 3D 3 1 2 Implicit 2D surfaces Similar to implicit 3D surfaces variety of 2D implicit surfaces are available in UI All 2D built in surfaces can be seen in figure 3 1 61 e Line The very first surface is Line It is similar to a Plane in 3D It is infinite and is defined by a center and normal For visualization purposes the infinite line 1s displayed as a line segment of A finite length depending upon the size defined by the user When Line tine button is clicked the Create Line dialog box appear as shown in figure 3 9 Note that 2D topology lies on the XY plane and hence the center and normal fields require only two coordinates x and y to represent the line The size field require a single real positive number which defines the length of the line i Y axis 0 0 1 0 1 Get workplane parameters Cancel Apply Figure 3 9 Line dialog box The workplane data can also be used to create the line surface by clicking on the Get workplane parameters The center of the workplane is copied to the center field of the line The workplane X axis is used as the normal of the line and the workplane diagonal length is copied to the size field of the line e Circle Circle is defined by its center radius and power Click on the Circle button e in the 2D tab of Create section Figure 3 10 shows the Create Circle dialog box which appears on the right side panel The center field require tw
155. of the longest to the shortest side in a cell It is a kind of local measuring done individually on each block irrespective of the neighboring blocks The aspect ratio value can range from to infinity Ideally it should be equal to to ensure best results By default it takes the range from 1 to 100000 e Skewness Skewness is always considered as the most apt measure of the mesh quality Skewness determines how close a cell or face to the ideal one 1 e Equilateral Skewness is measured from 0 to 1 A skewness of 0 indicates an equilateral cell best and a value of 1 indicates a completely degenerate cell worst A skewness up to 0 9 is widely accepted for computation e Warpage The warpage is a measure of the angle of a face which is defined as the angle of the normal vectors of the two planes generated by cutting through the diagonal corners of the face Ocheck uses 12 possible measures for a cell s faces to define the warpage angle of the cell The warpage angle is measured from 0 to 180 degree 5 6 Grid Toggling Section The Grid tab can hold many grids in the same space If the previous grid is not removed from the Grid tab the current grid which is loaded will overlap the previous grid Just as how the surfaces are selected as current grids can also be selected as current User can toggle between grids grid blocks and sheets from the Show Hide section located in the right side panel below Toggle display section as shown in fig
156. oints in the other direction That is the direction opposite to the surface created This ensures that the surface passes through the intersection Fourth one is the tangent magnification which helps in controlling the height till which the orthogonality has to be maintained The last option under advanced option is the height ratio which controls the maximum height of the surface 4 11 Gridding Process GridPro is well known for its revolutionary ability to generate grids from a topological basis one that is not encumbered by detailed geometric demands decisions or judgements GridPro requires no manual construction of geometric pieces such as block edges or faces or their associated pointwise distributions All gridding is done in one automated process there is no separate process for surface grid generation or surface to surface intersections Even within the context of a wireframe there is no projection algorithm required to send wireframe edges or faces onto the geometric boundary of a physical region Such projection algorithms require tight constraints upon the placement of wireframe corners the antithesis of true topology which relies upon a much looser and more flexible structure Grid generation takes place when the user starts Ggrid a transformation process to the topology code file with extension fra The resulting grid is optimized to be smooth and nearly orthogonal throughout an entire region and to be properly clustered to a
157. ollowing situations are considered to be regular on surfaces 3 d an edge on a single surface having two neighboring blocks and an edge on the intersection of two surfaces having only one neighboring block Any other surface edge is a singular surface edge and should be avoided in the design For 2 d cases things said about edges can be said about corners Thus the topology design in figure 4 88 has 4 singularities on the surfaces They are the 4 corners of the outer box A better design should avoid them and it is shown in Figure 4 89 In some situations insisting on using regular corners or edges on surfaces may result in bad topology However one does not have to use singularities on surfaces to solve the problem An alternative is to redo the surface division Region to be meshed Figure 4 88 Topology with singularities on surface 129 Figure 4 89 Modified topology without singularity Based on the effects of these the singularities are split into 3 types They are mildly mediumly and very severe singularity e Mildly severe singularity A singularity is ranked with the neighboring blocks and its surface assignments A corner is fixed if it is assigned to two or more surfaces So a corner can be fixed only on the surface intersection For an ideal block structure there should be only two edges emerges out a fixed corner in case of external surface intersections If there are 3 or more edges emerges out of a fixed corner
158. ology is valid It has no singularities Topology ts invalid Figure 2 68 Invalid topology status Cancel Figure 2 67 Valid topology status 2 4 Workplane Toolbar e Workplane As discussed before the workplane is the heart of creating and visualizing three dimensional topology It allows you to place topology around behind and below objects For example if you want to create a wireframe of a cube enclosing a sphere you need a device that can move you around the six faces of the cube The workplane allows you to place topology at any x y Z coordinates in space The plane can be rotated and translated to fit any position The 43 workplane is infinitely long however to facilitate easy operational use GridPro represents the workplane as a finite rectangle represented in plum color as shown in figure 2 69 This rectangle is called the workplane rectangle It can be shrunk or expanded in order to work on a global or local scale V Workplane shown in plum colour L Figure 2 69 Workplane shown in plum colour The workplane should be thought of as a tool that guides your cursor Cursor movement is always along the workplane In other words although you see the cursor move on a flat two dimensional screen it is actually moving on the workplane Essentially the cursor is attached to the workplane regardless of the position or size of the workplane rectangle Before you input or move topology always think of
159. on axis that you provide Two planes will automatically be positioned so as to bind a truly cylindrical region The position of these planes depends upon the length of the cylinder Figure 4 39 shows the cylinder macro dialog box First two fields topology type and resize in the dialog box are same for all the macro options Rest all fields in each macro box require you to input dimension values belonging to each macro 100 7 Cylinder esat Wireframe Surface Topology Wireframe Surface _ Default Resize Default Size X axis Y axis Z axis Center 0 0 0 Axis 0 0 Length 1 Radius Ok Cancel Figure 4 39 Cylinder dialog box Figure 4 40 Ellipsoid dialog box e Ellipsoid The Ellipsoid macro enables you to create an ellipsoidal shape region with a center axis and radius Sphere is a special case of ellipsoid when all the three axis have the same radius sphere is created By changing the radius value in any one of the axes an ellipsoid of different shapes can be created Figure 4 40 shows the Ellipsoid dialog box As mentioned above dimension field requires a center axis and radius value in all three directions These fields can be either filled manually or automatically using the resize drop down list by choosing one among the list which best suits your need e Rectangle Only if a 2D workspace is opened 2D macro options are enabled You cannot create a 2D macro in a 3D worksp
160. on discussed above is executed If mirror transformation is enabled all the transformation such as translation scaling and rotation are disabled Both mirroring and the rest of the transformation cannot be done together If the mirroring has to be done it should to be done after the other transformations Mirroring 1s done with respect to the center and normal of the symmetry plane The center and normal of the T1 symmetry plane can be provided in the respective fields A group of surfaces can be transformed using the transform tools available in the topology tab explained in the section 4 5 The surface transformation tool also helps in orienting the periodic surface In addition to specifying a period user should specify the axis about which the xpolar and xyz object are periodic However no part of the xpolar surface should lie onthe periodic axis The x axis serves as the default periodic axis However the axis can be changed by defining the translation and rotation properties in the transformation dialog box 3 4 8 Settings Orientation 1 sided with auto ort Property Default _ Advanced options E wall OFf i Il l x d g wall spacing 1 sided with auto ort 1 sided with ve ort 1 sided with ve ort 2 sided with auto match Stretch ratio Multi grid Label 2 sided with ve match 2 sided with we match 2 sided without match 2 sided with match Figure 3 33 Surfaces Set
161. onal reverse nest To do ribbon nest two layer of corners are required one is the layer on which the nesting has to be applied and the other layer which is created using the ribbon in order to retain the normal Once selected Surface Nest dialog box opens as shown in figure 4 112 Nesting group Select group Y Ribbon group Select group Special group Select group Y Num extrusions 2 O Max possible Ratio 10 o Outer group Select group Y Length group Select group Y Num length smoothings 1000 _ Should add wrap layer at the end Figure 4 112 Ribbon nest dialog box 146 The nesting group is the corner group which contains the layer of corners from where the nesting should be applied The ribbon group is the corner group which contains both the nesting group corners as well as the corner layer next to it i e corners generated using the ribbon The special group is the corner group which contains the corners where the nesting should not be applied The number of layers that needs to be created can be provided in the number of extrusions field The number of corners will be reduced with each layer If the corners cannot be reduced further the same number of corners will be created in each layer till it satisfies the given number of extrusions The distance length between each layer can be provided in the ratio field in the form of ratio Grouping the corners is always an important task in GridPro to do any operation
162. ons such as Create Edit and Check Repair Create section includes all the built in surfaces available in GUI both 2D and 3D Edit section include those tools which are used for modifying the already loaded surfaces Check Repair section includes tools that helps to check whether the surface is sufficiently smooth enough to be used for gridding process and also performs the modification based on the requirement In this chapter all these tools will be discussed 55 3 1 Surface Types As mentioned above Implicit and Explicit surfaces are classified based upon their surface definition e Implicit Surfaces Implicit surfaces are defined as equal potential surfaces of a scalar valued analytic function of the x y z position vector These surfaces are defined by the equation u x y z 0 Hardwired into GridPro are four special cases the plane cylinder ellipsoid and periodic surfaces Plane refers to as plane surfaces Cylinder refers to cylindrical surface Ellipse and sphere refers to as ellipsoid surfaces Periodic surfaces are rotational symmetric and translational symmetric surfaces e Explicit Surfaces Explicit surfaces are defined by parameters GridPro contains four explicit surface types the linear quad tria and tube surface types Explicit linear surfaces are single patch bilinear parametric surfaces or surfaces composed of multiple patches of bilinear parametric surfaces A quad surface is composed of unstructured qu
163. opy plane and the plane center for these planes would be Plane center the origin fo jfo jo Plane normal 4 5 3 Scale fo jf ja Scaling can be done by giving the scaling Ok Cancel Apply center and the ratio of scaling in all three directions Figure 4 75 shows the dialog box of the Scale button You need to provide the center of scaling in the center field and the ratio of scaling in the ratio field Each axis is provided with a separate field Unlike rotate and mirror there are no pre defined options for scaling Figure 4 74 Mirror tab dialog box Center 0 Ratio 1 Figure 4 75 Scale dialog box 4 5 4 Transform All the above discussed transformations are put together in this transformation tool Figure 4 76 shows Topology Transformation dialog box As you can see you can translate rotate and scale both the surface and or corner group Unlike the above transformations you don t need to keep a group active but the corners and surfaces should have been grouped in some group The dialog box provides fields to input the groups group numbers to be transformed for both corner and surface group Next is the translation I where the translation coordinates can be provided to translate the surfaces and corners Then scale where the scaling ratio is given Unlike scale button you cannot define the center as well as ratio on all 3 directions By default the origin is used as scaling center and the constant ratio is used for the
164. r edge surface edge of the grid grid sheet or geometry can be picked using the left button of the mouse to set that point as the center of rotation COR Note that when there is no object under the mouse the mouse is still under the selection mode and the next mouse click is used for the COR selection Also note that workplane is not treated as an object and hence cannot be selected using this option Reset Define At origin Model All Figure 2 44 Pick drop down list The center of rotation can also be picked using custom right click menu of the entities in the graphics window By holding keyboard shortcut P key and clicking on any point on any entity you can pick center of rotation Instead of picking you can fix center of rotation to the center of view volume or center of screen by using Reset Fe Pick drop down list By selecting Origin tA you can fix center of rotation at origin of co ordinate system You can also fix the center of rotation to the mass center of model by selecting Model option in Pick menu By selecting ALL under Pick will set center of topology as center of rotation Else you can define the x y and z co ordinates for center of rotation by selecting Define in Pick menu Figure 2 45 shows the dialog box of Define COR option 31 A aXxIs Y axis Z axis Position MA 0 o Ok Figure 2 45 Define COR dialog box 2 3 10 Probe You can get the information about topological surface and grid e
165. ra name You can change the default frequency of saving the topology from the Settings option in the File menu bar At the same time it also saves a file automatically with _auto undo It is the topology file which is having the state before which you did any undo or redo operations This file can be used to retain a session even after closing a session or if the current session has got crashed This file is overwritten every time you open the UI in the same working directory You can access _auto undo stack file in Topology tab from Load Undo stack Ye option 24 Once a grid is generated or you want to access the generated grid you can load that in Grid tab or Property tab from Load Dgrid option You can load multiple grids in the GUI 2 3 3 Save When you are working on any topology in GUI at any point of time you can save your a an work using Save buttonSe Using Save DEntire Topology option under Save menu in Topology tab you can save your topology When you save a topology you save information related to surface files its location and its association to wireframe in addition to the wireframe It allows you to save with your specified file name with extension fra You can also save a part of your topology which is kept in particular group for more information on groups refer section 4 3 to perform that you can use Save Corner group a in Topology tab which prompts you with a dialog box asking a particular group and the file name with
166. reframe D 0 fhe BA with just a click on it using the Center te button in the workplane toolbar Click on the Center button and click on any surface or corner edge to transform the center of workplane to the clicked position 48 2 4 5 Workplane Fill Fill operation of workplane serves as a visual aid Clicking on the Fill option will leave the workplane rectangle shaded in translucent white Usually the Fill operation is most useful when a side of the surface is clipped and you want to better orient your eyes to the view screen Essentially the Fill operation locates the workplane for you and allows you to view better 2 dimensional slices of a surface as seen in figure 2 75 Fie Fie fill a ee gt a ee fill Figure 2 75 With and without fill for workplane l 2 4 6 Section Figure 2 76 Section Drop down list Workplane is useful for viewing surface and grid cross section The options under Section EEN drop down as shown in figure 2 76 can be used to look inside different parts of surfaces and grid By positioning the workplane so that it cuts through a surface grid you can actually clip away part of that surface grid by selecting the ve option from the dropdown list Only the portion of the surface grid on one side of the workplane will remain The other side of workplane can be seen by selecting ve option from drop down menu The previously showing portion of the surface grid will disappear while the other
167. rent Click on Fill Util button located under Check Repair section in Surface tab Figure 3 39 shows the dialog box of Fill button Create path around the region that needs to be filled using the path creation options available then click on Fill button in the dialog box Tria surfaces will automatically fill the hole Filled holes are not part of the surface until the modifications are saved using Save Modifications button Select Select path Cancel Save modifications Save path Fill Figure 3 39 Merge Surfaces dialog box e Right Click Menu Apart from the properties options the often used options are kept under surface right click menu as shown in figure 3 40 gt Surface info shows the information on surfaces such as id type label position and group number to which it is grouped as shown in figure 3 41 gt Center of rotation picks the right clicked position on the surface as center of rotation of the screen 81 amp 3 2 E J Cai ch Figure 3 40 Surface Right click menu gt Make current option used to select any surface current Selecting this option on gt a current surface will ignore the selection Surface 0 info Center of rotation Make current Hide Delete Orientation Transform Display type Surface td Surface type Label Complete info s0 tria sedan_cf stl tmp l groups 0 Figure 3
168. rent properties to a grid based on the solver selected under Solver menu in the top menu bar Each solver has a separate list of properties depends on the selected solver the corresponding property list can be seen in the property drop down list Properties are assigned to faces and blocks separately Additionally the Properties tab contains operations similar to those in the Grid tab User should be aware of what each operations does as well as what each operation displays on the drawing area 174 k Solver View Help Surface Tools File E Property v All 7 we g Ggrid Validity ZA p Wireframe Surface vV Pf Pick Q t ing Snap Jey Frame gt Property sheets Current J B I Select Display Workplane Grid X a A Redo Zoom Unzoom Probe AoA a Undo Load Properties section Property Wall Solver section TIR SULREURRRESER TER ER rr TETRLITEN A i RERERRWERRRERUDERROLED fi ttrt MA RRUURURUALERLLLD We Ge we we we Mf Gweceis o fi EE seroma Se Num Blocks 12 Num Cells 47616 tab ies Propert Figure 6 1 6 1 Properties Section Properties tab on In 10n sect In properties section which is located below toggle display id blocks can be d 3D properties as shown in ri and g the right side panel the properties assigned to the grid sheets 1es an 2D properti e t into two
169. require some inactive corners in addition to active corner for reference 110 4 3 6 A KEY In addition all the buttons for grouping operations keyboard shortcut such as A key available to select a sheet from active group of corners It helps you to visualize how corners are propagating through out the topology You can pick a cross sectional sheet from active group of corners by holding A key and clicking on active edge near the sheet which you want to select You can use and options along with A key to add or subtract sheets from active corner group Figure 4 57 shows the sheet selected after using A key Figure 4 57 A key 4 3 7 Surface Grouping Tab You can access surface grouping options by depressing Surface Groups tab in Groups section In surface group tab similar to corner groups there are nine groups 6 grouping operation buttons and 11 grouping display modes which functions exactly to similar to comer group options Surfaces belonging to active groups are displayed in different colors whereas inactive surfaces are displayed as white grey color to distinguish between them In addition to all these operation ALL group 1s also available located below selection operations in surface groups tab It displays all surfaces in GUI as active surfaces and also you can use this ALL group to add all surfaces to active group 111 Surface Groups Selection Figure 4 58 Surface Groups tab 4 4 Topology Modifying Ut
170. res of a grid that can be seen The outline of each block is displayed once the grid blk tmp file is loaded The outline of a block is simply the boundary of the block formed by its edges The center of each block is the center of mass of each block and is represented by a small square The skeleton of a block is the lines connecting the indexed center of the block with the 169 centers of the block s bounding edges 2D or faces 3D Each block skeleton is drawn in its own color When collected each block skeleton forms a skeleton for the entire multiblock grid The skeleton represents the minimal amount of information required to show a broad representation of a multiblock grid Also the skeleton illustrates the flow of the block structure better than the outline In three dimensions the number of lines produced by a skeleton is 6 while the number of edges of a block is 12 Figure 5 27 displays the broader physical representation provided by the skeleton The flow is the block connectivity that is witnessed as simple curves in the skeleton In the case of the circle with a hyper quad topology the skeleton shows one circular loop and four radial like lines The grids can be viewed as a collection of outlines and or a collection of skeletons However only one of these display forms can be used at a time in order to avoid the screen clutter a B fT ir Figure 5 27 Blocks outline and skeleton of a sphere Grid skeleton w
171. retained Next is the concave corner group if the singularity is in concave corner group it can be solved using surface by surface wrap without internal surface as mentioned above Heal button also solves the surface by surface wrap in the concave region So corners with singularities in the concave region should be grouped and given in this field You can either solve all the three singularities at a single time or step by step The next three options are the check box indicating which singularity has to be solved By default it solves both mediumly and very severe If you want to solve mildly severe in addition to that then enable the checkbox of mildly severe The next option is again a check box to input whether to create buffer layer or not By default it creates a buffer layer you can avoid creating it by disabling the checkbox The last option is the ratio which determines the newly created corner position 4 8 Topology Optimization Utilities Topology optimization utilities are used to enhance the topology in order to optimize the grid according to the user s need Three tools are classified under Optimization utilities such as Density Nest and Enrich Density allows you to refine the grid by modifying the number of grid points Nest allows you to refine specific regions in the grid with cells of 1 1 connectivity Enrich utility or compact enrichment utility refines the grid in a particular region without affecting the farfield 4 8 1 Dens
172. rid to the file blk tmp The Ggrid process really represents the running of a schedule file with extension sch Thus when transferring topology data from one terminal to another be sure to include the schedule file with the fra topology file If there is no sch files GridPro automatically creates one with the default value A sample schedule file is shown in figure 4 119 The schedule can be modified in the GUI itself by modifying the parameters in the grid schedule pop up which is explained in section 2 3 153 HThis 15 a sample schedule file You may edit it step 1 g all 1 880606x step 16668 c all 1 6 8 C all 1 6 24 r 3 1606 w write f blk tmp write D 8 f dump tmp Figure 4 119 Sample schedule file Like topologies grids can be saved under user defined file names Because GridPro saves grids to the default file blk tmp you must alter the name blk tmp when you retrieve your grid if you wish to save it under a user name To assign a user name to a grid access the save grid as option in the grid tab explained in section 2 3 You can arbitrarily choose the extension name for any grid file By altering the file name you will be able to retrieve your file whenever you wish because all other grids produced will be saved under bik tmp Each grid file is accompanied by a connectivity file This connectivity file specifies how the grid blocks are connected and has the extension conn GridPro automatical
173. rking where undo cannot Figure 2 34 Tag topology state drop be done after closing the session unless you load an undo stack down list file but the tag topology state can be reverted back to a previous tags and the topology can be modified Once it is reverted back to a previous state all the tags after that will be removed Clicking on the button will show the drop down as shown in figure 2 34 To tag a state select Tag Current Topology State you will be prompted with a pop up where you need to input a name for tagging the state In order to revert back to a previous state select Revert to a Previous State a window will pop up as shown in figure 2 36 which contains all the states that were tagged in the current fra file which is loaded Selecting a state and clicking on ok will revert the existing topology to the selected state and the tags after that will be removed from the file 26 Corners linked Corners created Input a new topology state Pe OK Cancel Figure 2 35 Tag current topology state dialog box Figure 2 36 Revert to previous state dialog box 2 3 4 Delete You can delete any surface any topological entity or any at cs it l F entity related to grid using Delete button te in all the tabs located Current surface next to the Save option in the Global Dock A current surface can be Inactive surfaces deleted using Delete Current surface gt in Surface tab or in come dias Topology ta
174. rkplane or surfaces or grid Projection often helps in visualization and positioning purpose There are different aligning tools available in GridPro that are grouped under Align button When Align button is clicked Align Wireframe dialog box opens as shown in figure 4 77 There are five options divided under two tabs 1 e Align To and Align On Align To provides option to project the group of corners to the Workplane and Grid Surface Workplane WP center Figure 4 77 Align To dialog box Figure 4 78 Align On dialog box 123 4 6 1 Align To Workplane The align to workplane operation projects the active corner group to the workplane such that the center of mass of the active corner group and the workplane are relative Figure 4 79 shows the projection of corners to workplane Note that projection on workplane does not place the corners at workplane position Workplane AA Figure 4 79 Before and after aligning to workplane 4 6 2 Align To Grid Align To Grid is a kind of projection that synchronizes the position of the topology corners and the edges with the grid blocks existing in the grid tab A multi block GridPro grid should exist in the grid tab that should match the blocking pattern and the block count of the topology that has to be projected Both the topology and the grid should exist in the current session of the GridPro Figure 4 80 shows the topology before and after sync 124 Figure 4 80 Before and after ali
175. rner group Select group Refinement level 2 ha Use smoothing Output file Select file Ctrl F Cancel Apply Figure 3 29 Refine dialog box The three options under RefineBein button give the user a better control to modify the surface better The first option feature corner group is a corner group on which the refinement will not be applied This helps in retaining the sharp features of the surface where the refinement is not required The second option is the number of refinements and the last one is use smoothing that can be enabled disabled by toggling the check box If smoothing is enabled in addition to refinement the surface will be smoothed out with increased number of triangulations 3 4 4 Scale eal button in the Edit section next to Refine done by giving the scaling center and the ratio of scaling in all three directions Figure 3 30 fine button It can scale either current surface or active surface group Scaling can be shows the dialog box of the Scale Sele button The center of scaling needs to be provided in the center field and the ratio of scaling in the ratio field Each axis is provided with a separate field 75 Define Current surface Current surface group Av axis Y axis Z aXiS Center 0 o o Ratio 1 i ing Cancel Apply Figure 3 30 Scale surface dialog box 3 4 5 Merge If one surface can be split into two surfaces using Split tool two surface
176. roups e Angle Angle button in Check Repair section helps to find out the surface cells angles If the feature angle is more than 45 degree then it has to be repaired to avoid getting skewed grid If path formed by feature angle is a closed one it can be split using Split button under Edit section Split operation offers three options one is based upon path formed by feature angle other is path created manually and the last one is by trimming the surface cells 70 In Angle tab under Split Bion as shown in figure 3 23 a surface is split based upon feature angle If calculate automatically 1s selected it will split the current surface if it is forming a closed path with the feature angle more than 45 Another option in Angle tab is specify threshold angle which would split the current surface above the specified angle if it forms a closed path Press Apply to split the current surface Calculate automatically Threshold angle 45 J Ok Cancel Apply Figure 3 23 Angle tab for Split button e Curve In order to split up the surface form a closed curve around it using options available in Curve tab under Split button as shown in figure 3 24 Creating curves is an essential tool in the surface manipulation process A curve is either a straight line between any two adjacent surface nodes or a straight or bent line composed of paths between any two nodes Curve appears as olive coloured lines Endpoint of a path appears as a
177. rward nest creates a high density topology from a low density topology whereas reverse nest works in the opposite which creates a low density topology from a high density topology A complete topology is required to apply Reverse nest This helps in coarsening as the topology moves from the geometry to the farfield Figure 4 103 shows the dialog box of the reverse nest Input group Select group Feature group Select group Num extrusions 2 Offset length 0 1 Extrude Spherically Cancel Apply Figure 4 103 Reverse nest dialog box The input group contains the corners in the outermost layer of the topology assigned to the outer boundary The feature group contains the corners where the reverse nest should not be done The number of extrusions are the number of layers the reverse nest has to be done The ratio is the ratio of the distance at which each extrusion should be placed It s the distance between the each successive layer given in terms of ratio Other than the feature group corners the general reverse nest omits the corners on the intersection of two boundary surfaces from reverse nesting Enabling the check box of extrude spherically make the reverse nest to account the corners at the intersection of two surfaces Figure 4 97 shows how the forward nest works whereas reverse nest works in the opposite direction is in 2 directions similar to area nest 139 4 8 3 Compact enrichment Whenever the grid
178. s having same boundary faces can be merged into one surface using Merge tool located under Edit section If Merge button is clicked a dialog box opens as shown in figure 3 31 Select the two surface numbers that have to be merged and provide the output file name and click on OK It will merge the two given surfaces and it will be replaced by a single merged surface Specify Surface Select id hy Surtace Select id I Output file Select file Ctrl F Cancel Ok Figure 3 31 Merge Surfaces dialog box 3 4 6 Copy Copy tool a is also only applicable for implicit surfaces that are generated in GUI It is used to duplicate current built in surface to create a new surface and append it to the current topology This is very useful if a new surface with the properties similar to the Current surface is needed When this option is clicked a dialog box corresponding to the current built in surface opens in the right side panel so that the surface position can be modified and append the surface For instance to create a plane parallel to the current planar surface it can be duplicated 76 and the center can be modified appropriately The copy option can be undone and the operation is also stored in the undo stack 3 4 7 Transform 2 ae Transform option Mar works fine for any surface in GUI whether implictit surfaces such as plane line circle cylinder ellipse ellipsoid xpolar or xyz or explicit surfaces
179. s the color by block color by sheet and color by IJK operations The color by sheet operation colors each displayed sheet differently there is one color on each sheet The color by block operation colors every block face in each sheet differently Each face or slice is created when I J or K is a constant Color by IJK operation allows you to color faces and slices depending on which coordinate is a constant By default the color by sheet option is selected as shown in figure 5 11 Block Sheet Figure 5 11 Color dialog box with Sheet tab Figure 5 12 Color dialog box with Block tab Similarly you can also display the blocks with different colors either by index or quality Selecting the index will display all the blocks with four different colors which is the default option If color by quality is selected all the good blocks would be displayed in green shade and the bad blocks in red color The reference values for the good quality would be assumed from the default values of Quality button 5 2 Preprocessing Utilities 5 2 1 Extract In addition to visualize the grid in Grid tab you can also generate the topology from the grid Extract button in the Tools section located in the right side panel of Grid tab is used when you have a structured grid without the corresponding TIL code and still want to use GridPro to relax it Extract allows you to generate topology wireframe surfaces from the available structured grid The necessary co
180. screen axes using the Set gt t button The set menu contains eight options as shown in figure 2 72 Each option allows you align workplane axes with world axes screen axes by transforming the normal of the workplane For example if you select the World X A operation the normal of the workplane will align with the world X axis As a result the workplane will snap to the yz plane The World Y tp and World Z om operations work similarly The Screen X tot Screen Y r and Screen Z E option aligns the center of the workplane axis with the center of the respective screen axis 46 It can also be positioned anywhere you want if you have the center and normal of the Tm T h desired location using the Define aE option under Set drop down For define option the normal and center fields define the position of the workplane Like any plane the workplane can be positioned by inputting the coordinates of a normal vector to the plane and the coordinates of one point on the plane The point on the workplane for which you provide coordinates becomes the center of the workplane You can input x y z coordinates of the normal vector in the normal field and input x y z coordinates of the point in the center field Like position of the workplane the size of the workplane can also be defined using the size field By default the size is defined as the current workplane size that is calculated automatically once the Define button is clicked and it
181. se button the left mouse button you can translate the workplane along that axis You will use this imprecise but simple method of translation most often to position loosely the workplane If you wish to rotate the workplane about one of its axes click on the axis with the left mouse button Notice that the specified axis becomes thin Then drag one of the two fat axes with the rotational mouse button the middle mouse button in order to rotate the workplane about the thin axis You can change the size of the workplane rectangle by dragging the one of the four violet vertexes either inward or outward When you position the cursor on a vertex the cursor becomes a blue square with a center dot 45 Four rectangle vertexes highlighted in violet color used for resizing the workplane Workplane Y axis highlighted in green color Workplane X axis highlighted in pink color Workplane Z axis highlighted in dark blue color Figure 2 71 Workplane with Handles switched on 2 4 1 Set Topology creation in three dimensions is sufficiently complex GUI provides you all the required tools to help you create these topologies easily The workplane allows you to place corners anywhere in space Also the workplane helps you orient yourself World X World Y World Z Screen X Screen Y Screen Define Fit to group Figure 2 72 Set drop down list GUI provides you the shortcuts to align the workplane axes to global axes and
182. sed upon the propagation mode selected Corner Sheet inserts are created using a feature of the insert mode The three insert modes are All Group and Edge All these three modes are shown when the Insert button is depressed By default the ALL mode is on After depressing the Insert button click on an edge where you would like to insert The insert sheet will propagate till the two boundaries of topology i e a corner is created on that edge at the point you clicked and proportionally on every edge topologically parallel to the edge you clicked as shown in figure 4 25 It can also be done using the shortcut key by holding the I key on the keyboard and click on the edge where the insert has to be done 5 SS Figure 4 25 Insert propagation in All mode If Group propagation mode is selected and a corner will be created on that edge at the point you click and proportionally on every edge in the active group that are parallel to the edge you clicked The inserted corner won t be propagated beyond the active corner group as shown in figure 4 26 Figure 4 26 Insert propagation in group mode If Edge propagation mode is selected which means 1 edge insert i e it allows you to input a single corner on an edge in order to split that edge a Figure 4 27 Insert propagation in edge mode 95 If mode All or Group is ON and click on an edge not only are corners formed proportionally along every edge parallel to the one you c
183. shells When the Ggrid process creates a grid GridPro carves up the region inside each block into IJK coordinates index coordinates in order to create a smooth grid The IJK coordinates of each point are integers each node thus lies on a lattice point The maximum and minimum values of these IJK coordinates appear on the boundary of the block Note that IJK coordinates differ for each block within one grid Lt E Lo 7 La Er Ek HHTHH Figure 5 1 Grid blocks Figure 5 2 Grid blocks with one face highlighted A face is the grid about a boundary of a block More technically a face is a network of links along indexed IJK lattice points such that I J or K is a maximum or minimum A slice is a grid that cuts through a block More technically a slice is a network of links along indexed IJK lattice points such that I J or K is any constant integral value between a certain maximum and minimum A sheet is simply a collection of linked faces or a collection of linked slices A sheet composed of linked faces is called a face sheet and a sheet composed of linked slices is called a slice sheet A face sheet composed of the faces of the outer boundaries of all outer activated blocks is called a shell which is a sheet A face sheet composed of the faces of the outer boundaries of some outer activated blocks is called a partial shell which is also a sheet Notice that sheets can take on many shapes 156 r SAAANA ARANAN
184. sity This is useful when you want to increase the size of the graphics window Even though graphics size might have been changed but the objects in the graphics window may be dis oriented and it needs to be updated by simple left click in the drawing window which would redraw all the graphics objects and reevaluate the view volume appropriately Common tools Toolbar Shortcuts Figure 2 21 Dockwidgets drop down list 22 3 Help menu To view this document while working on UI you can select the desired format under Help menu Though the short help is very useful to view the help content sometimes the user may need to look at the entire documentation to get a broad picture of the classification of various tools in the GUI Thus the offline help is packaged along with the software and can be accessed by you readily The help content can be either viewed in HTML format using a web browser or as a PDF using the PDF reader Figure 2 22 shows the options in the drop down of Help menu in top menu bar View Help in PDF format View Help in HTML format Figure 2 22 Help Menu When the option View Help in PDF format is clicked the default pdf reader is launched and the documentation file in pdf format is opened using this application Similarly when the View Help in HTML format is clicked the default web browser is launched to open the HTML documentation files 2 2 4 Surface Tools The Surface Tools menu has tools used for creating surf
185. specified dimension New button is only active in topology tab as topology can only be defined in topology tab Set the dimension of the topology 3D Figure 2 28 Set dimension dialog box 2 3 2 Load The Load button helps to load a topology or a surface or a grid file which you have created or you were working on it previously Usually you would be having a geometry which have been modified in Cadfix or it would be in a format which can be directly loaded into UI hence to load a geometry or surfaces into UI use Load button Pin the Surface tab located below New button You can load the surfaces from Topology tab even Load gt surfaces option allows you to load a single or multiple surface files from the working directory in one of the GridPro formats The supported surface formats are quad tria tube lin and tmp When you load many surfaces into UI each surface is assigned an id numeric value starting from Q on the basis of order it 1s loaded into the UI Topology Surfaces Template Undo stack Figure 2 29 Load drop down list in topology tab Topologies which are saved in fra format can be loaded into the UI from Load gt Topology a option in the Topology tab Load DTopology allows you to retrieve topologies in 23 fra format All user defined topology files must have the extension fra Figure 2 29 shows the drop down list of Load button in the global dock of the topology tab In addit
186. surface is flipped and the surface is toggled Note that since the visibility flag of the current surface flag is modified the surface remains hidden visible when the current surface 1s scrolled further Note that the surfaces which are hidden are referred as inactive surfaces 2 6 Toggle Display Section As discussed in section 2 1 the right side panel is divided into many sections Of those sections the toggle display section is one of the common sections present in all the tabs at the right side top From the toggle display section you can hide show the surface topology grid and workplane related objects in the graphics window Figure 2 79 shows the toggle display section with various options By default it is collapsed click on the title bar of the section to expand the section gt Iw Surface gt Topology L Grid gt Others Figure 2 79 Toggle display section 5I e Surface In the toggle display section first branch is Surface By default surfaces are visible only in Surface tab and Topology tab Sometimes you may want to hide the surfaces and the surface related objects while building the wireframe for better visualization or you would desire to view surfaces to compare it with grid GUI provides two ways of toggling the surfaces either locally or globally The toggle display section helps in toggling globally while the toggle surface section will help in toggling locally which is discussed in section 2 5
187. t click on density button then click on one of the parallel edges All parallel edges will then highlighted with red lines Once the density button is clicked and the edge whose density has to be changed is selected Change Edge Density dialog box opens as shown in figure 4 95 which contains three fields the edge current density and new density fields The edge field reads the selected edge id and the id s of the corners to which the edge is connected with The current density field displays the current density of the parallel edges The default setting is 8 per set of parallel edges The edge and current density fields contain fixed information you cannot type new information in these boxes The new density field illustrates the new density of the edges you wish to alter Therefore you must type the desired density value of the edges in this field The dialog box has 3 confirmation buttons such as apply ok and cancel Clicking on apply applies the change in density and retains the dialog box so that you can assign density for other edges without clicking on density button again Clicking on ok will apply the change in the density and close the dialog box Clicking on cancel will close the dialog box without any modification Edge Current Density New Density Figure 4 95 Edge density dialog box The greater the density of the topology the longer the Ggrid process will take to complete For two dimensional grids every time you double the d
188. t is performed only on the blocks of a grid The three buttons which are enabled in Blocks tabs works as follows the third button 1 e show all grid blocks E will turn the display on for all the grid blocks in the GUI The fourth button i e show only current grid blocks i will hide all other grid blocks not sheets in the GUI and will show only current grid blocks The fifth button is toggle all grid blocks will flip the visibility of all the grid blocks NOTE Switching off the grid sheets or grid blocks in toggle display section will also switch off the corresponding object in the Grid sheets section but the vice versa is not possible 5 7 Grid Trimming Utilities Besides viewing the whole grid GUI has an option to view a desired portion of grid and save it with the desired name Trimming feature helps to achieve this Both the blocks and sheets can be trimmed as per the requirement Operations related to trimming are grouped in the Trim button lim located in the Tools section Clicking on the Trim button will open a dialog box as shown in figure 5 26 User can select the trimming tools for blocks or for faces by selecting one of the tabs in Trim dialog box Select Blocks for trimming blocks and Faces for trimming sheets By default Blocks have been selected for trimming Figure 5 26 Trim dialog box 5 7 1 Blocks Each grid block has a center an outline and a skeleton The outlines of blocks are the first visual featu
189. te Faces It outputs an error message as shown in figure 4 68 if remove sheets is not possible because of different adjacent layers To avoid such mistakes in grouping use A key to group the corners which gives the sheet of corners without much of human effort 117 4 4 5 Face Exclusion You have learned what wrap is and how it is used in the topology This subsection describes exceptions arising from the rules stated previously regarding the wrap of a surface In order to account for these exceptions you must exclude faces of a wireframe A face here is defined as the area enclosed by four corners and the edges among them Face exclusion 1s necessary in two cases first you must exclude faces so that GridPro can read correctly the dimension of a surface being prepared for wrapping For example a wireframe rectangle can be thought of as a string of four segments a one dimensional wrapping or as a quadrilateral a two dimensional wrapping Therefore you must specify the dimension of the wrap In order to convey to GridPro what you are wrapping you must exclude faces of a wireframe when the edges of those faces are to be wrapped as one dimensional segments 7 After snapping to screen Face excluded before wrap External wrap after a face is After snapping to screen excluded Figure 4 69 Wrap on face excluded wireframe Second you must exclude faces in order to exclude a portion of the wrap Figures 4 69 illustrate how wrap is aff
190. the screen to the corner position An axis similar to the global axis whose center appears on the corner which represents the center of rotation is fixed in that place NOTE Corners and edges are also used in surface creation which will be discussed in section 4 10 4 2 2 Link Ver When you want to create an edge between two corners Link tnk button can be used Depress the Link button located on the left side tool bar under Create section in Topology tab Move the cursor to one corner and click on it using left mouse button in order to select a corner the cursor must become a ring then move the cursor to the other corner and click the left mouse button An edge should appear between the two corners as shown in figure 4 20 Figure 4 20 Corners with and without edges In order to create a string of edges all you must do is depress the Link button for the duration of the process and click the mouse strategically By clicking the endpoint corner of the string clicking on every successive corner you wish to link and finally clicking the other endpoint corner of the string you can form many edges quickly and efficiently as shown in figure 4 21 Figure 4 21 Strings of corners linked Simply dragging a box after depressing the Link button around the group of corners that has to be linked can also create edges as shown in figure 4 22 Note that it will not create a closed loop in order to avoid creating a triangular block 93 Fi
191. the surface External flow geometry The external surfaces are surfaces which acts as the boundary surfaces for a grid It does not have grid on other side The internal surfaces are surfaces that have grid blocks on both the sides 1 e Surfaces which are defined inside the grid to represent the fluid solid regions or to enhance the grid lines would have grid on both sides Thus at that point there would be two normal vectors one pointing to each side So surfaces that have grid on both sides are internal to the grid and as such are quite naturally called internal surfaces All the implicit and explicit surfaces except the periodic surfaces xpolar and xyz can be used as internal or external surfaces depending on the need Orientation 1 sided with auto ort Property Default _ Advanced options E wall Off wall spacing Stretch ratio Ce Muti gid C sided with ve on 1 sided with auto ort 1 sided with we ort 2 sided with auto match Load the surface only once 2 sided with ve match 2 sided with vwe match Ok Cancel Apply 2 sided without match 2 sided with match Figure 3 15 Surface Settings dialog box Figure 3 16 Orientation drop down list Label Orientation can be changed using the Settings ed button The dialog box of settings button is shown in figure 3 15 The Drop down next to the Orientation heading appears with 8 29 66 29 options when clicked is shown in figure 3 16 The items are a combina
192. ther current or not current The current piece is in sea blue The split pieces can be scrolled through and any piece can be selected as current surface using the previous and next buttons To save the current piece click on the Save button Often segmenting surfaces necessitates using many paths saving these paths will guide the user when the surface has to be revisited The Save path button saves a path to the file name Path has loose ends Please close the path Cancel Figure 3 26 Split error message ve Aw X 4 j P AANA A y Tay 4 Tr s af o Poi ie D w Dead ar Poo o gt Fa T ear Ti e Pikta Pain 1 pete seg saa ow p k KANANE E LTP MATA a AN ree 5 4 rata A PAIA Fa sr oF sl A BA il K 2 ek Le DAAT TNA A a E ELAD CROAT ROY UCR SLA ATER Wart gt H N hea oe ve at ATA s Mg s9 P Te i ry L gt Bi a Ri H 2 fare ove ey er 4 KY z sr ey 7 a iY DET SA TaVAY v e a Ee ate a Current surface is segmented into 2 pieces Figure 3 27 Surface split into two pieces 73 e Trim The third tab under Split button is Trim as shown in figure 3 28 It is similar to Curve instead of selecting path surface elements are removed to split the current surface Surface elements can be added or removed one by one from current surface by using A button After switching on button cl
193. ths and angle value is shown in maximum angle field Additionally a message will appear at status bar specifying the angle as shown in figure 3 20 To delete the paths created by the Angle operation press the Clear button ea z File View Help Surface Tools Solver amp Surface Topol DRR E Sa a e evr af BSB New Save Delete Frame Snap Pick All Current Wireframe Surface HA ARAARA m Load Undo Redo Zoom Unzoom Probe Select Display Workplane Grid Feature angle path formed in baby m B pink colour by pressing Next button Plane Cylinder Ellipsoid Periodic significant number of times Selection 2 all a AS me amp Increment Maximum angle 140 Clear Nee Cancel Status bar shows current feature angle Num Blocks 0 eqll surtaceia 0 IiI fp Help Figure 3 20 Feature angle path formed on Current surface Current feature angle 140 68 3 4 Surface Reconstruction Utilities GridPro has a specific definition of a surface So user has to modify a read in surface to adapt it for use on GridPro GridPro contains features in the form of CAD functionalities that allows to perform this modification All the tools that are used for surface reconstruction or surface modifications are grouped under Edit section of Surface tab in the GUI 3 4 1 Thin Sometimes geometries loaded into the GUI have fine triangulations which will slower the GUI performance In such cases
194. tings dialog box Figure 3 34 Surface Orientation drop down menu Load the surface only once Ok Cancel Apply Settings tool is applicable for all the surfaces in GUI It is used for defining orientation property and clustering parameter It can also be used for labeling the surfaces If the Settings tnd button is clicked Set Surface parameters dialog box opens as shown in figure 3 33 The orientation can be changed using the drop down list next to the orientation It has a list of options as shown in figure 3 34 Orientation parameter guides the Ggrid engine to grid which side of the surface If the surface has one sided orientation it can have grid blocks only on one side of the surface which is automatically determined by the grid generation engine If the surface has two sided orientation it is an internal surface with grid blocks on both sides of the surface By default all the surfaces manually appended to the topology have one sided orientation But the surfaces read from an existing topology macro will retain their orientation from the loaded topology Note that when the surface orientation is changed it is saved to the undo stack since it changes the state of the topology Boundary condition or property can be set to a surface by selecting one of the options from the drop down list under property It inherits the properties based on the solver selected in the Solver menu The properties which are set on the 78 surf
195. tion in Surface tab 3 3 1 Border Border olive colour path around the entire border of the current surface By switching off the button will remove the same path The border for current surface is shown in figure 3 17 Figure 3 17 Surface boundary border 3 3 2 Angle The Angle operation illustrates surface cell s levels of significance The angle between the normal of the two planes slanting off from a surface cell determine the cell s level of significance The smaller the angle the larger the significance level Angle tool is available with two option such as incremental and above the specified By the default Angle tab is displayed as 5 shown in figure 3 18 when the Angle nd button is clicked 67 Angle Incremer Angle Increment Threshold angle Maximum angle Figure 3 18 Angle tab dialog box Figure 3 19 Increment tab dialog box Once the threshold angle is given it calculates the angle in all the surface nodes and creates a path in baby pink color on the current surface wherever the cells are having angle more than the specified value To generate a smooth grid feature angle more than 45 is not desirable Another option is Incremental available in Increment tab as shown in figure 3 19 Press Next to display the path and maximum feature angle of the current surface Every time you press Next all cells with the next lower level of significance will be highlighted with baby pink colour pa
196. tion of side side auto and Ilside amp 2 sides Each item dictates the direction of all vectors normal to the surface 66 The direction is outward and the direction is inward If a surface is oriented in the 1 sided ve direction the normal vectors at each surface point points to the side of the surface If a surface is oriented in the 1 sided ve direction the normal vectors at each surface point points to the side of the surface Similarly if a surface is given Isided auto match orientation GridPro will automatically calculate which side has to be meshed using the topology positions of its assignments In order to impart double orientation to surface select 2 sided with auto match In the grid generation process GridPro will optimize the grid quality and produce a grid sheet that is smoothly embedded within the overall grid and it would be hard pressed to find any discrepancy 3 3 Surface Probing Utilities Geometries created using CAD software are sometimes not perfectly suitable for CFD analysis as it may be having some leaks or patches Sometimes geometry is perfectly fine just require some modifications so that it can be readily used by grid engine The GUI contains operations allowing you to manipulate the GridPro read surfaces In surface tab two tools are classified under surface probing tools namely Border and Angle Both the tools are located under Check Repair sec
197. ts A separate section called Assignment consists of the tools that help in assigning the corners to its respective surfaces The tools that help in creating the surfaces using the corners and edges are classified separately under surface creation utilities which are located under Surface Tools menu This chapter also explains about the gridding process 4 1 Topology Building Like all other multi block grid generation programs GridPro requires you first to sketch out the topology for a surface before inputting that topology You must know how a volume will be decomposed into blocks GridPro can only work with your results not create those results In other words you should decide upon the pattern of grid points before you can instruct GridPro to generate the corresponding grid The first step in creating any topology is always to define the region which must be gridded Then decomposing the boundary geometry into surfaces and the surfaces describe a block pattern the resulting wireframe topology must represent this pattern Although the real life objects are 3 dimensional creating topology in two dimensions first better prepares you for creating topology in three dimensions in case of symmetry in 3rd axis In two dimensions gridded blocks are represented by convex quadrilaterals or quads In three dimensions gridded blocks are represented by convex hexahedrons or hexes When you create a quad or hex GridPro will automatically recogn
198. up Rotate topology Group deals with rotating the active corner group and surface group to a desired angle with the given rotation center and the axis of rotation It can rotate along the default global axes such as x y and Z axis and about workplane Once the dialog box is opened select the corresponding axis to which the active corner and or surface group has to be rotated then enter the angle of rotation in the respective field and click on apply to rotate The center of rotation is taken as origin for these axes By default the user defined option is selected which allows you to rotate a corner and or surface group about the user defined axis The user has to define the center of rotation the axis of rotation and angle in the respective Group C Z axis C Workplane User defined Angle 90 Center C 0 0 Axis oO jo J Cancel Apply Figure 4 71 Group tab dialog box fields Selecting the workplane option will rotate the corner and or surface group along the workplane axis You need to mention the angle of rotation The center of rotation is evaluated from the workplane center and the axis of rotation is always considered as workplane z axis Remember that it rotates the topology but it does not create a copy e Faces Rotate topology Faces which is used for rotating the given wireframe using the angle number of instance and the pitch This tool can be useful where geometries have same cross se
199. ure 5 22 Local toggle section has three tabs one for Grids one for Grid blocks and the other for Grid slices By default grid slices tab is visible Click on erid blocks tab to see the grid toggle tab blocks toggle tab The names of all the grids loaded into the GUI can be seen in both blocks and grids tab 166 fe a FS surface 3 surface 4 gt surface 5 gt surface 6 surface 7 2m ger A ca ae surface 1 OX surface 2 gt Slices 4 All sheets Figure 5 23 Grids tab alijsurtaceia 0 I gt P Tag Topology State Help rids a Allg Num Blocks 12 Num Cells 47616 z Q D N D T 3 S a BAB AS SEC RSS Eas Q a O O om a o 3 S e g OD A H oN ANNA RE RENRRSERECRREOGUUEREEURCRENUECCUE 0 faw av O 5 gt 2 i O O Q Q Sio SSS SF cbveaesSu Sup g dia amp WHEA ae eer seot gages p S OED Ay 2 BRS BVTE sg Mae Ge esuy 8s Wh D o ABSESSE Loo BiB 23 2585 eR Ss 8 k o Pees Pegs sty Eu E ai SERS v E M Ss BD w g QO 72 ec Ee j HSSo Se E E 3 EEEH HUTT HITTITE ONG CO eo OS eS OO woe BES pan WO 3 CTT TETHER Ww So lte Ss OLGM CEPR S aw HET TTT eos amp S oD E Mt TT kes oO N WY Ss Q O a D 5 ES t em L ao gt Q 57g THN 3 CL s o g Oa g ao b gt S ae Q O d _ GIN Foi n a YS SFE WE oe aT XE HEBER EBS Bar FMWOon fF TH SME gt Q 3 Om so gt D oOo Z e amp O M O O oO
200. urfaces The Intersection tool should be used first to obtain the corners at the intersection The corners created is the path group to be used Figure 4 117 shows the dialog box of the Internal surface Path group Select group Inverted surfaces group Select group Type Algebraic surface file name internal_surf quad Advanced options Method BSPLINE CONTROLNET Num smoothings N Tangent magnification Height ratio Figure 4 117 Internal surface dialog box 150 Path group is the corner group in which the corners created at the intersection of surfaces is grouped The surface would be created using the normal at the intersection so if some corners normal has to be changed then it has to be grouped separately and input it in the Inverted surface group option There are two kinds of algorithm that can be used to create a surface such as Algebraic and Variational which can be selected under Type drop down list These three are the basic options that a user can be easily used to create a surface There are also advanced options available which can be enabled by clicking on the Advanced options check box First option is the method which is a separate algorithm for creating the surface which will be applied after the algebraic variational type A list of 6 different methods available under the method drop down list Next is the number of smoothings to be applied on the surface created Next is the N which is number of p
201. urfaces for whichever option is selected Note that the visualization type can also be changed set by right clicking on the object and selecting the appropriate visualization mode will be explained later In this case this mode which is set manually from the right click custom menu overrides the mode selected through this display menu You can reset the manually set visualization modes of all the objects using right click custom menu in the graphics by using Reset Display When the visualization mode is reset the display mode of the surfaces uses the mode selected using display menu 36 For example when the all surfaces display mode is set to HLR and a surface is set to Shade using the right click menu the surface display mode is reset to the HLR when the reset display mode is clicked 2 3 15 Wireframe Clicking on this button will toggle the entire wireframe and its related objects such as corner id and errors if it 1s on 2 3 16 Surface Clicking on this button will toggle all the surfaces and its related objects such as border path selection and feature edges 2 3 17 Workplane Clicking on this button will toggle the workplane and its handle 2 3 18 Grid Clicking on this button will toggle all the grids loaded into the GUI and its related objects such as blocks sheets block id s and its orientation 2 3 19 Start Ggrid In this global dock commands related to starting and stopping ggrid are added for convenienc
202. where the workplane is positioned If the rectangle is too large you will see nothing because you are looking inside the rectangle In this case zoom out the screen By contrast sometimes the rectangle will appear as a white speck In this case zoom in on it All the tools related to workplane are located in the left side toolbar as shown in figure 2 70 and can be accessed from all four tabs e Workplane Axes Similar to global axes there is a set of workplane axes that is represented in pink green and dark blue color Along with axes there are four violet squares each of which is placed on the vertex of the workplane rectangle as shown in figure 2 71 The pink axis is the workplane x axis the green axis is the workplane y axis and the dark blue axis is the workplane z axis When you bring the mouse cursor near to an axis the cursor will transform into two curved arrows Make sure the cursor is changed into two curved arrows before you try to click on any axis 44 Aligns the workplane axes with world axes Fits the workplane to active corner group Fix the workplane z axis to screen z axis Centers the workplane in different ways Shades the workplane rectangle Clips surfaces and grids Section Hides Workplane axes i Handle Figure 2 70 Workplane toolbar Usually workplane axes are referred as handle as it helps you to translate or rotate in graphics window By dragging an axis with the translating mou
203. which is on the side that is to be gridded Differences between correct topologies and a discussion of what topology to use will be covered later In general preferred topologies about angles between O and 90 degrees have the structures shown in figure 4 2 Cd F aar i I Fi f Fi ri F Fa Fi F i Fd F Fi F Fi r Fi oOo F N Fi H f w fi i F F Fi baeancnaaaaa Aan m w m m Figure 4 2 Topology for angles between 0 and 90 degrees Angles between 90 and 180 degrees typically have two different structures These structures are shown in figure 4 3 the topology on the right side of the figure is used more often for these angles 85 Sees ese eaanaae ee we eaeeeeaeeaes Figure 4 3 Topology for angles between 90 and 180 degrees Preferred structures for angles between 180 and 270 are shown in figure 4 4 ew ee eneeces Fa i Pe Figure 4 4 Topology for angles between 180 and 270 degrees Angles between 270 and 360 degrees can have several structures the most common of which are illustrated in figure 4 5 Figure 4 5 Topology for angles between 270 and 360 degrees Notice that all of the topologies are created using convex quads and all quads have full face matching Figure 4 6 incorporates ideas you have seen 86 Figure 4 6 Example showing the above ideas incorporated If a surface is smooth decompose the surface as you normally wou
204. white square Figure 3 25 illustrates examples of paths Save path Segment Figure 3 24 Curve tab for Split button 71 WIL NL NNT AT ANT AUNT MCAT tt Figure 3 25 Various ways a path can be created my In order to create a curve user can either use the toggle path E or add path T k button Toggle path _ _J button helps to pick path between two nodes one at a time After depressing the 5 button click with the left mouse button on between the two nodes that will add to the curve Keep clicking between the nodes to add it to curve Similar to toggle path Ej add path iy button allows to create curve Instead of picking path between nodes click on nodes and it will form a curve from the starting node to the second node that has been selected It will try to select the shortest distance as a path between the two nodes If the line connecting the two points is not along a surface cell GridPro will automatically create a zig zag curve among the intervening cells Notice that once used the toggle path ty and add path ty button will remain depressed and activated until it is re clicked Thus after clicking two nodes clicking a third will extend the path that was just created By repeatedly clicking nodes while add path iy button is depressed a long and precise curve can be created as per the requirement The three le operations to the right of the add path button manage paths The remove path __ operation
205. xtension A quad file consists of total number of points coordinates of each point number of quads in the surface the node numbers of the quads and the property id of the surface if it has The positive side of the quad surface is determined by the first quad in the quad list It is the side where when one faces the first quad the listing order of the points that defines the quad rotates anti clockwise Figure 3 12 shows an example of quad surface with two quads node 5 node 4 node quad node 6 node node 3 Figure 3 12 Surface with two quads 64 e Lin The only explicit 2D surfaces that can be created in UI is in lin format lin are linear surfaces defined by an I J array of points for some I and J in the file The bilinear interpolation is used to determine the surface points within the array cells No collapsed or merged data points are allowed It is represented either by dat or lin as an extension In GridPro the curves generated by the controlnet curves option in 2D builtin surfaces panel are saved in lin format Apart from that dat and lin files which are generated from the CAD packages can also be loaded into GridPro with some modifications in the file 1 e the total number of points should be mentioned in the first line of the file Figure 3 13 shows an example of linear file with 6 surface pieces Figure 3 13 Linear file with 6 surface pieces e Tria Tria is the only explicit 3D surfaces that cannot be g
206. y and in the defined region This nest utility is further divided into 4 different tools having dedicated tab each works in a different way The Nest button Net is located in the Edit section of the right side panel in Topology tab The first three deals with the nesting as explained above and the reverse nest works opposite to the nesting which is helpful in coarsening the grid as it moves towards the far field High density group Select group Low density group Select group Direction group Select group Refinement levels 3 Cancel Apply Figure 4 96 Nest dialog box 135 e Forward Nest Forward nest can be achieved only on a complete topology You need to provide high density group i e where the density should be more low density group i e where the density should be retained as original directional group which guides the nest tool along which direction it has to be nested mostly it s along the wrap direction and finally the number of refinements which decides the number of layers of nesting Figure 4 97 shows how the nesting is done on a topology locally You need to provide the group number in which each group has been grouped into in the respective fields As you can see for each layer three corners are substituted for each corner on the previous layer Figure 4 96 shows the Nest topology dialog box Low Density Directio n Group Levels of Refinement 22 High D
207. y clicking on the graph icon next to each parameter The report will only give the maximum value on each parameter but more often the interest is to see a range of values and also the location of those bad cells in the grid To find the bad cells in a given range click on the Advanced tab Four parameters are provided as shown in figure 5 21 with which the bad cell s location within a given range can be examined They are Folds Aspect ratio Skewness and Warpage You are flexible enough to check either one of the parameters or all the parameters in a single check by enabling or disabling the check box before each parameter Once it is enabled the minimum and maximum range of that parameter can be given The cells which fall under that range will be displayed in the UI with a new grid consisting of only these cells under the name qcheck hex grd Note that for each parameter the range of min and max values varies which are already displayed in their respective fields Report No of Blocks No of Cells Advanced No of Folds Folds Worst Skew Max Warpage 0 0 180 Max Warpage M jin L Aspect Ratio 1 0 100000 Ewaluate Load bad cells Figure 5 20 Quality report dialog box Figure 5 21 Advanced tab dialog box e Folds Fold are defined as the inconsistency in the positioning of the grid nodes of a cell with respect to the neighboring cells 165 e Aspect ratio Aspect ratio is a measure of the ratio

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