Home

ELMER Front's User Guide

Contents

1. Boundary Level L RESINA MA es gt verte Figure 2 24 Mesh example The arrow from the top left down to the right corner highlights the relation between different levels The boundary level L3 edges and vertices inherits the appropriate body level L2 mesh density value if no definitions for them has been made Similarily the body level inherits the model level L1 density value BODY 1 For Body1 a quadrilateral mesh has been defined Edges 1 and 3 are devided into 10 segment and edges 2 and 4 into 20 segments and the total number of elements is 200 BODY 2 For Body2 the user has defined a triangular mesh Vertex5 has its own mesh density value and the mesh is denser around this vertex If the user would not have defined any value for Vertex5 it would have inherited an average value derived from the density values at the edges 5 and 6 62 ELMER Front s User Guide 2 12 4 Define mesh Model Level L1 Mesh name iesea Data Po ssz R ies Model mesh H m o oo Current Default Mesh scaling factor pon j Current Default Mesh structure Mesh density Generate mesh Figure 2 25 Define mesh window ELMER Solver has a multimesh capability This means that different equations can be solved using different meshes If variable values from one equ
2. AA Mesh structure i fe Chapter 2 ELMER Front 67 e Nof elements 1st and 3rd edge the number of elements sege ments for the first and third edges in the Edges listbox e Nof elements 2nd and 4th edge the number of elements sege ments for the second and fourth edges in the Edges listbox 2 12 6 Mesh Density The Mesh density window opens by pressing the Mesh density button in the Define Mesh window These definitions affect the mesh at the boundary level L3 Mesh density values can be set at edges or at vertices However a parameter set defined for an edge cannot be applied to a vertex and vice versa They have different masks This is mainly because a nof elements type definition does not have any meaning at vertex level Mesh Define mesh Mesh density Boundary level L3 ies Boundaries Mesh density sets V7 Vertex y y Attach Detach Add Update Delete Body kettie Boundary Kettle srf Name Mesh name Meshl Values for mesh density parameter Mesh density value type C None MeshH Relative Nof elements Mesh H m 0 0075 Relative mesh H 1 0 Nof elements Cancel Apply Figure 2 27 Mesh density window 68 ELMER Front s User Guide Mesh density value type radio buttons are used to select between three different input options e None deactivates values on this level e Mesh
3. Equation s Equation name s is needed Solver Procedure si s2 Library s1 and function s2 names are needed Variable s Variable DOFs i Status Line Name s Process Table Name s Variable name s is needed Degrees of freedom default 1 Status line name for the eq default UDn Process table name for the eq default UDn NOTE These properties define how the variable of the equation is displayed in the Initial Condition and Boundary Condition panels where it is added automatically for entering initial values and Dirichlet boundary condition values To see the role of each property and the default values see the field property explanations below NOTE The variable field is labelled autmatically based on the variable name but the user can also set the label here Can Be Procedure 1 Can Be Table 1 Hide 1 Index Type s Label s Label Width i 100 ELMER Front s User Guide Label By Coordinate 1 Initial Value r Subpanel i Unit Label s Widget Width i Panel field definitions given under an equation section are active only for the specified equation There can be multiple panel sections in an equation section 1 Panel s Panel name s is needed Eai Add panel definitions here End Panel End Panel keyword is needed End Equation End Equation keyword is needed 5 4 2 The Panel section When a panel section is outside any equation section the field defini tions affect all equations Ther
4. Element order Linear Meshing method MovingFront Background mesh Delaunay Nof elements 2nd and 4th edge Edges Mesh density value type Meshing seed edge C None MeshH Relative Mesh H m 0 0075 Relative meshH 1 0 Cancel Figure 2 26 Mesh structure window The Mesh structure window opens by clicking on the Mesh structure button in the Define mesh window Parameters entered in this window define the mesh at body level L2 On top left is the list of all bodies and the mesh structure sets attached to them The name of the currently active mesh is displayed in the Chapter 2 ELMER Front 65 Mesh name field This field is not editable The selected body can be included or excluded from the mesh by using the Include body in mesh checkbox The mesh element type can be selected using the Triangle and Quad radio buttons Ifthe quadri Mesh structure lateral mesh type is selected the mesh size parameter entries on Mesh structure the right side are activated as Define mesh Element type shown in Figure 2 12 5 Tiange Quad e Element order Linear setting creates three nodes triangular and Element order Linear four nodes quarilateral elements Meshi Boel ae Parabolic setting creates six nodes spl cia __MovingFiont triangular and eight nodes quadri Background mesh Delaunay lateral elements Mesh density value type e Meshing method Basic mesh i ing st
5. e Drop removes a file from this list The file itself is not affected e Open in ELMER Post opens the selected file in ELMER Post The following fields are non editable information fields e Post file the full path for the postprocessor file e Equations the equations solved in the result file e Modified time the last update time for the result file e Last run status status of the process which updated last the out put file e Comment this comment field is only for this session and it is not saved in the model file 2 14 7 Process table When other ELEMR modules are started in ELMER Front informa tion on these processes is collected into a process table This table can be opened using the Process table command or the Process button in the main window This table displays information on the current sta tus of a process and the user can also control the process using the command buttons in the process table window Process table columns e Process the name of the process e Nbr an internal id number for the process e PID the operation system process id if available e Prior the process priority level e State the current process state Value are ALL DONE process ended succesfully FAILED process failed during the processing KILLED process was ended by the user SUSPENDED process is suspended and is waiting to be acti vated RUNNING an active and currently running process e Start End process start and end
6. any actual processing of the model Other fields are either collected from other panels for reference or are simple model object counters but Minimum edge size field needs some explanation It is the smallest edge size which is used when a linearized CAD geometry is transmitted for the ELEMR mesh generator This information may be useful when setting the mesh density parameters for the model Note Nof is an abbreviation for Number of 2 11 2 Body info Body info command opens an information table where the physical dimensions and the number of mesh elements for each body can be checked Data in this window cannot be edited 2 11 3 Body list Body list command opens an information table displaying a list of all model bodies Button colors are the same as the body colors and body names are used as button labels This list may be used to match the bodies in the data entry lists with the bodies in the Model window 2 11 4 Initial conditions Body forces Materials Initial conditions Body forces Materials In the Initial conditions window the user can set initial values for model variables In the Body forces window the user can set the external forces affecting to model bodies 50 ELMER Front s User Guide In the Materials window the user can set material parameters for the bodies Next figures display the layout for these windows The workflow in these windows is essentially the same and in the following
7. e Equations nof bodies having an equation total nof bodies in the model and names for the defined equations e Timesteps total nof timestesp defined for the problem In a steady state case the maximum nof iterations e Materials nof bodies having a material definition total nof bodies e Initial cond nof bodies having an initial condition total nof bodies e Body forces nof bodies having a body force definition total nof bodies e Outer bc nof outer boundaries having a boundary condition total nof outer boundries e Inner be nof inner boundaries having a boundary condition total nof inner boundries e Meshes nof currently active meshes Chapter 3 ELMER Geometry File format 85 Chapter 3 ELMER Geometry File format 3 1 Introduction This appendix describes the ELMER Geometry File format This ge ometry file is for implementing basic geometries which do not actually need the use of a full featured CAD program The geometry prim itives which can be defined in this file are limited to polylines and circular arcs but in practice it is possible to define quite complicated geometries with these primitives The data in the file is devided into sections and these sections must come in a specific order in the input However some of the sections are optional Each section starts with a keyword and ends with the keyword End Data items within a section also start with a specific keyword Below is the list of the sec
8. if one of the variables in a user defined equation were Chapter 5 ELMER Definitions File format 103 named as Oxygen and a material panel field named as Diffusivity were defined a Pre index would create a field named as Oxygen Diffusivity and a Post index would create a field named as Diffusivity Of Oxygen These name would be used also in the sif file No default value Initial Value s r i 1 Fields initial value This value should match the value type of the field No default value Label s Field s label in the panel No default value Label By Coordinate 1 If true a coordinate symbol is added to the field s label The x coordiante corresponds to the first degree of freedom etc This property is meaningul only for the variable of the equation and it is not applicable to the normal panel fields Default value is False Label Width i Label s width in characters This property can be used to align widgets in the panel by defining the same label width for each field to be vertically aligned Default is the length of the label string Label Unit Label Subpanel i Field are grouped into subpanels columns in the panels A panel can can be reasonably devided into 3 or 4 subpanels depending on the maximum field width label width widget width Default value is 1 but in the Equation panel the first available subpanel is 2 which also the default value the first subpanel is res
9. 33 2 9 4 Bodies Bodies to be displayed can be selected by using the Bodies menu com mand or the Select bodies button in the main window 2 9 5 Boundaries Boundaries of x X 2 Water smtr gt 3 Inner X 4 Kettle stf x 5 Bottom X 6 Kettle smtr None Ele ls Boundaries to be displayed can be selected by using the Boundaries command in the Display menu When a boundary is double clicked in the listbox its draw mode is turned off or on The All and None settings can be activated by pressing the Apply or Ok buttons 2 10 Problem menu In this menu the actual problem definition is started Most of the definitions here concern the whole model and are not specific to bodies or body elements 34 ELMER Front s User Guide Figure 2 9 Problem menu 2 10 1 Model Name and directories The Model name and directories command opens a window where the model name and the file directories can be entered These directories are used when reading saving or searching data files related to the model Model name and directories Boiler e 7uanrenzougajsorie r E E OK cancel At Figure 2 10 Model name and directories window Note it is possible to use spaces in the model and problem name but because these names are used also in filenames it may be safer to avoid spaces Spaces can create problems especially when filenames
10. El a ELMER Front session as follows d mesh ll e Load mesh if mesh file is available Leioa mesh but currently not loaded this commands reads the mesh into ELMER Front e Unload mesh this commands removes the mesh from the memory Sometimes it may be useful to remove a large mesh from the memory before starting other ELMER modules Note If mesh is very large it could be useful not to read in the mesh automatically This autoload behaviour can be controlled using the Settings command in the Edit menu or through the Autoload mesh button in the main window 2 7 3 Save model The commands for storing model files and related data are the following File Save model file Ctrl S Save model file As e Save model file saves model file emf file in the model directory e Save model file As same as previous but the name and location for the model file is asked instead of using the default name and location Note When model definitions have been modified model data should be saved Otherwise updated model data is not available for other ELMER modules The model file is saved automatically when ELMER Solver is started if Auto save model file setting is turned on as it is by default This concerns also all other processes started from the Run menu excluding ELMER Post 2 7 4 Browser windows These windows are meant for browsing the files file editing is not possible e Browse model file displays the model file
11. H activates the Mesh H field to be used for enetering an absolute mesh density value in this level e Relative activates the Relative mesh H field to be used for ene tering a scaling factor for mesh density in this level The actual mesh density value for this level is the product of the scaling factor and the body or model level density value e Nof elements the fixed number of elements segments at the edge Mesh log file When the mesh is generated a log file is created if this process out put setting is activated An example of this file is shown in Figure 2 28 This and other logfiles may be viewed using the Process table command in the Run menu Define mesh Generate mesh C walkthrough B oiler ElmerMesh2D log 1 Al ES Mesh input file C walkthrough Boiler MESHDIR Meshl Boiler mif 4 Mesh output directory C walkthrough Boiler MESHDIR Meshl Parse 0 Node 1 0 0033 Node 2 0 0033 Node 3 0 0033 Node 4 0 0033 Node 5 0 0033 Node 6 0 0033 Node 7 0 0033 Node 8 0 0033 Node 9 0 0033 Node 10 0 0033 Conversion completed Generating Body 1 completed Generating Body 2 completed Nodes 952 Elements 1786 ALL DONE Freeze Figure 2 28 Mesh logfile example Chapter 2 ELMER Front 69 2 13 Solver menu 2 13 1 Solver settings The Solver settings window is shown in Figure 2 29 Settings for the Navier Stokes equation are displayed In this example all fields have their
12. The operating system can be either Windows NT 4 0 or Unix It is recommended that the user has a computer system containing 64 Mb memory at minimum Installed ELMER version requires approx imately 40Mb disk space Contents Contents 1 Overview 1 1 ELMER Capabilities o o 1 2 ELMER Structure 1 3 ELMER Work flow 2 ELMER Front 2 1 Input to ELMER From 2 2 ELMER Front main window 2 3 General user interface features 2 4 Starting ELMER Frodmt 2 5 ELMER Front settings file 2 6 ELMER Front definition file 2 7 FUE MEU hind Ge is A a 2 8 Edit ment 203 34 cee e pol eA eid o 2 9 Display menu o 2 10 Problem menu 2 11 Model mem 2 12 Mesh menu 2 13 Solver meda 2 14 R n meiu o srpa a e ea pa a aa A 2 15 Window mea aaa aaa 000086 216 Help men sea E 2 17 Model window toolbar 2 18 Model Window 2 19 Control toolbar 2 20 Message area i Ea 2 21 sStatusvareas E eck see a SE 3 ELMER Geometry File format 3 1 Introduction 2 0 0 0 0 02 20 ee eee 3 2 The format Laa enya aed A ee ee eee es 3 3 An example file 4 ELMER Front settings file format ELMER Front s User Guide 5 ELMER Definitions File format 5 1 5 2 5
13. default values Solver settings Al ES Navier Stokes C Heat equation Variable Flow Solution Update Mesh Mesh STABILIZATION M Direct 2 BANDED LUMPED MASS MATRIX I Iterative tal BiCGStab LINEARIZATION COI Max iterations soo 5 O Tolerance 1e 008 Tolerance 12 005 Residual output 1 Relaxation factor fh Use Newton Iv Preconditioning ILUO Newton after iteration ls Coupled egn tolerance le 005 Newton after tolerance fo 01 Cancel Aol Figure 2 29 Solver settings window Each equation system in the model is solved by a separate solver These solvers can selected using the radio buttons on the top of the window The advection diffusion equation differs from other equations because it can solved for multiple variables Each of these variables is solved by a separate solver These solvers can be selected by pressing the Variable button and selecting the corresponding variable from the list 70 ELMER Front s User Guide Solver settings Solver settings Al Xx C Navier Stokes C Heat equation Advection Diffusion Variable Oxygen Update Mesh Y Oxygen phi Carbon Figure 2 30 Advection diffusion solver example When all data fields for the solver are entered or modified the settings for the solver are stored by the Update button All solvers have initial values which are adequate for standard cases However it may be that the solution
14. e Direct this radio button selects a direct solving method For relatively small problems a direct solver is nor irect 9 BANDED mally faster For any larger problem P Iterative it is usually better to use an iterative bene s ees A solver The version for the direct solver can be selected pressing the button at the right side of the radio but ton e Iterative this radio button selects an iterative solving method Current options are the following Iterative fol BiCGStab v BiCGStab TFQMR e BiCGStab BiConjugate Gradient Stabilized e TFQMR Transpose Free Quasi Minimal Residual e CGS Conjugate Gradient Squared e CG Conjugate Gradient e GMRES Generalized Minimal Residual e Max iterations the maximum number of iterations for the iterative solver e Tolerance an error norm threshold If the error norm is smaller than this number iteration is stopped e Residual output an integer value linear system residual is output for each Nth iteration zero value disables the output e Preconditioning using preconditioning normally speeds up the it eration however resulting in some overhead Options here are e None no preconditioning 72 ELMER Front s User Guide e Diagonal Diagonal preconditioning matrix Fast construction but not very effective e ILU Different level of Incomplete LU decompositions ILUO is the rec Solver settings ommended choice Max iterations 300 e Coupled eq
15. factors Calculate View factors command starts ELMER View factors pro gram It stores the result data in the View factors file defined in the Problem Datafiles window Note for large meshes this can be a time consuming process It creates a browsable logfile 2 14 3 Calculate Gebhardt factors Calculate Gebhart factors command starts ELMER Gebhardt factors program It stores the data in the Gebhardt factors file defined in the Problem Datafiles window Note for large meshes this can be a time consuming process It creates a browsable logfile 2 14 4 Solver This command starts ELMER Solver It creates a browsable logfile 74 ELMER Front s User Guide 2 14 5 Postprocessor Postprocessor command starts ELMER Post in a separate window 2 14 6 Select result file Select result file Al ES Add Drop Open in ElmerPost 3 See fl Post file Equations Modified time Last run status Comment This window is needed when multiple meshes are in use Because all result files are stored in the same directory where the mesh for an equa tion is stored it is necessary to specify the result for postprocessing in a multimesh case All postprocessor output files produced during the session are listed in the listbox Any of the files may be selected as the input for the postprocessor e Add opens a file browser for adding new files created in other sessions to the list Chapter 2 ELMER Front 75
16. file selection in the Settings window has to be checked off By default all changes in the solver input file will be overwritten when the model is saved for the next time This may be prevented by setting the Auto save solver input file checkbox off 2 8 8 Working directory Edit Working directory The current working directory can be set using this command This directory is used as the default model directory 2 8 9 User level The user level setting controls the amount of commands displayed in menus and the amount of warning messages displayed when working with the panels There are three levels available New users should first use the Novice level This level simplifies menus by displaying only the most essential commands It also protects againts unintentional loss of data by giving warning messages when modified panels are 28 ELMER Front s User Guide closed without saving the data etc The Power user level in contrast practically bypasses all warnings The Advanced and Power user levels speed up the work for experienced users Note The default level in the beginning of each session is the Advanced level 2 8 10 Settings Settings i e e e Figure 2 8 Settings window Chapter 2 ELMER Front 29 Settings command opens a window where current problem settings can be modified The setting parameters can be devided into five groups These groups are shown by numbers 1 5 in Figur
17. for the selected body in the figure 1 Kettle 1 Kettle eq shows that the equation number 1 is attached to the body number 1 It also shows the body name Kettle and the equation name Kettle eq Name in this field the user can enter or modify the name of an equa tion set Pressing the Update button stores the name The currently defined equations are displayed in the Equation sets list box An automatically generated equation sequence number is shown at the beginning of each line When an equation is attached to a body this number is also displayed after the body name 44 ELMER Front s User Guide When parameters for a specific equation are entered this equation must be first selected using the equation type radio buttons Pressing a radio button on area 1 opens the appropriate input panel on area 2 where the equation is defined in detail The Navier Stokes equation has been checked in the example below fi Navier Stokes Heatequation Stress analysis C Advection Diffusion Clear all Clear panel Clear entry Navier Stokes settings Calc hydrostatic pressure JE Turbulence model aj None 2 C KE KEClip le 006 E Proc Separate equation types in the currently active equation set can be turned on and off by using the checkboxes in the lower left part of the window In the example only the heat equation is activated others are turned off Navier Stokes settings NAVI
18. it is given without a preceiding String data type specifier Otherwise quotes are not necessary but it is safer to always quote the strings Quotes within quotes are not allowed A logical value can be either 1 meaning true or 0 meaning false 94 ELMER Front s User Guide In the following keywords are in the same order as they are displayed in the Settings window The meaning of each keyword is explained in the context of the Edit menu in Chapter 2 The keyword values given below are just for an example The user should of course enter own values for the keywords which he or she defines in the settings file Default Model Directory String elmer Models Default Cad Files Directory String elmer data cad_files Default External Mesh Files Directory String elmer data mesh_files Default Include Path String elmer input Default Log Directory String elmer work Default Results Directory String elmer work Should the settings stored in a model file used when it is loaded 1 Default Use Model Settings Logical 0 Auto Load Mesh Logical 1 Auto Save Model Logical 1 Auto Save Solver Input Logical 1 Command for an external logfile browser here in read only mode 1 Browser Command Chapter 4 ELMER Front settings file format 95 String C Program Files TextPad TXTPAD32 EXE r Command for an external editor for editing Solver input file etc Editor Command String C Program Fi
19. name For example if ELMER Front is started using the command ELMER model directory ELMER MODELS stepf low then the directory ELMER MODELS stepflow would be the default directory for model files If a model file stepflow emf were stored in that directory this command would automatically load this file into ELMER Front 2 5 ELMER Front settings file When an ELMER Front session is started values for various control variables can be initialized from an input file settings file This file is loaded automatically if a file named front esf is found in the ELMER HOME lib directory or if the user defined environment variable named ELMER _FRONT_ SETTINGS is set and contains any file name refering to a settings file The name for a settings file can be specified also in the command line when ELMER Front is started as explained above Settings files are searched and loaded in the above order and any later definition overwrites previous definitions The structure and the contents of this file is described in Appendix 4 2 6 ELMER Front definition file When an ELMER Front session is started values for user defined equations and panel fields can be loaded from an input file definition file A definition file is loaded automatically if a file named front edf is found in the ELMER HOME lib directory or if a user defined environment variable named ELMER FRONT_ DEFINITIONS is set and contains any file na
20. the directory name in the listbox and pressing ok button Double clicking the directory name opens a subdirectory list A When this button is pressed a selection list El Session Deen model opens Currently active type is displayed as E aoe i Swen the button label Available options are _ Settings model e Session the value defined for the session is used e Model the value defined in the model file is used e Settings the value defined in the settings files is used When the Save in model checkbox is checked the active value is saved 36 ELMER Front s User Guide in the model file 2 10 2 Datafiles paa The names for different input and output file can be defined in this window which is opened by the Datafiles command This window is shown in Figure 2 11 Datafiles Al E Model directory c walkthrouga Boiter Model file foiler emt Solver input file fboiler sit Mesh input file boiler mit Results directory c walkthrough Boiler ss i lt sS Result file Boiler dat Postprocessor file A Restart file EE Restart timestep position EE Gebhardt factors file cebhardtFactors dat SS View factors file fwiewtactors dat SS i Cance apor Figure 2 11 Datafiles window e Model directory information field not editable Model file information field not editable e Solver input file information field not editable Mesh input file information field not editable e Results dire
21. the Initial conditions window is used as an example Body forces 1 Kettle Figure 2 17 Body forces window Chapter 2 ELMER Front 51 Figure 2 18 Materials window 52 ELMER Front s User Guide Initial conditions 1 Kettle 1 Kettle init 1 Kettle init O Dele Figure 2 19 Initial conditions window In all these windows parameter sets are attached to the bodies The general workflow and the button properties were already described in the Equations window section Entry fields displayed on the window depend on the selected equation type When a body is selected only those equation type radio buttons are active which are relevant for the body And only those equation type buttons are visible which are relevant for the current problem For example if no flow equation on any of the bodies has been defined the Navier Stokes radio button would not be visible on these windows Initial conditions In Figure 2 19 Bodyl with the initial condition set Kettle init has been selected The Heat Equation radio button is shown selected Chapter 2 ELMER Front 53 Now the user clicks on the Body2 1 The Water named body is clicked on 2 The Water body row and the initial condition set Water init become highlighted 3 The Navier Stokes radio button becomes enabled and when the user clicks it entry fields for the flow equation are displayed Model Initial co
22. the radius A circular arc can be defined by the center and two end vertices or by three vertices 3 2 4 The Edge Loop section Edge Loop i the unique id number i must be given Edges i the edge ids in any order defining the loop End Note Although the order of edge ids in the input is not important these edges should always create a closed loop which does not interect with itself or with any other edges 3 2 5 The Body section Body i the unique id number i must be given Name s optional a string 90 ELMER Front s User Guide optional four integers 0 255 RGB values and an alpha value Color i Vertices il Polygon i the vertex indices defining the body Edges i the edge ids in any order defining the body Edge Loops i the loop ids defining the body The outermost loop must always be given first after that the inner loops if any in any order End Note The keywords Vertices and Polygon are equivalent Again the order of edge ids is not important but these edges should create a well defined edge loop 3 3 An example file The following example geometry is taken from the Boiler egf file which can be found in the directory samples cad_files in the ELMER distribution However some clarifying comments are added here This is also the same geometry which is used as an example in the ELMER User Guide It defines two bodies a kettle and the water in the kettle Only the left half of this symmetric geome
23. these cases the option to define boundary condtions at that specific level is needed It should be also noted that it is not possible to attach a boundary level condition to edges or vertices and vice versa because this conditions could contain values which are not applicable at these lower geometrical level For example it would not be meaningful to apply a flux constraint on a vertex Radiation boundaries For a diffuse gray radiation boundary one has to define a radiation target body For an outer boundary the target can be either the body itself or the Outside environment For an inner boundary the target body must be one of the parent bodies It is possible to apply a constraint defined at a boundary to boundaries in other bodies having similar equations as long as the target body is the same However if a constraint is applied to multiple bodies it is not any more possible Chapter 2 ELMER Front 59 to change the target body because this would create contradictions The only way to change the target body in these cases is to detach attachements until the constraint is again attached to the boundaries of only one body or body pair 2 12 Mesh menu 2 12 1 Background ELMER Mesh supports triangular and quadrilateral 2D element meshes Elements can be linear or parabolic and different bodies can have dif ferent mesh types However element types cannot be mixed within a body The structure of a triangular mesh is free T
24. times wall clock times For a 76 ELMER Front s User Guide running solver process the End field displays the number of currently processed timesteps e Duration total run time e W the rightmost W column is marked with an asterisk if the process created any error messages or warnings Process table ojx Process Nbr PID Prior State Start End Duration W ALL DONE OS 723 09 2 00 01 3 ALL DONE ALL DONE ALL DONE ALL DONE ALL DONE ALL DONE Figure 2 33 Process table Processes are listed in the order they were started The most recent process is on the top of the list All fields are info fields Below the process lists is an area where information on the currently selected process in displayed The actual contents depends on the process type Possible error and warning messages are also displayed in this area Process table buttons e Suspend the selected process is suspended paused e Resume resumes continues the process e Kill stops the process after confirmation Note the process name is not erased from the list e Delete kills the process and removes the process from the list after confirmation e Browse opens the log file if available for the selected process Chapter 2 ELMER Front 77 e Priority the process priority level can be set using this button Options are Favor GUI or Favor process These are descriptive values and the actual priority level transmitted for the operation sys
25. to define a structured mesh for a body and a triangular mesh for a body which is adjacent to this body However in these cases the structured mesh defines automatically the 60 ELMER Front s User Guide mesh density at the common boundary and the resulting triangular mesh may become quite artificial So mixing element types in one model is possible and in many cases quite useful but it must be done carefully These concepts are highlighted in the example shown in Figure 2 24 Labels In the Model window normal boundaries are labeled by sequence num bers and vertices with the sequence number preceded by the letter V Mesh element types ELMER Mesh2D supports the four mesh element types shown in Fig ure 2 23 A is a linear quadrilateral element B is a parabolic quadri lateral element C is a is linear triangular element and D is a parabolic triangular element Figure 2 23 Mesh element types 2 12 2 The three mesh definition levels e The Model Level L1 e The Body Level L2 e The Boundary Level L3 including also edges and vertices If no definitions has been made on L2 and L3 levels the model level L1 parameters are set as default to all meshes included in the model 2 12 3 Mesh example Figure 2 24 shows an example where each body of the model has a different mesh type Body1 has a quadrialteral structured mesh and Chapter 2 ELMER Front 61 Body2 has a triangular free mesh
26. used to add update and delete timestep set entries The time dependency type of the current simulation problem is set in the Time dependency box Options are Steady state and Transient In the Steady state case total iteration amount and the output fre 40 ELMER Front s User Guide quency are controlled by the following fields e Maximum number of iterations Maximum limit for the steady state iterations iteration is stopped even if the steady state conver gence criterion is not yet met if this limit is met first e Output interval Output frequency for steady state iterations For transient problems two basic timestepping schemes are available Newmark and BDF In the Newmark method the beta parameter can be freely selected but the three most common methods can be simply selected using the radio buttons for the Impilict Euler Explicit Euler and the Crank Nicolson methods These methods correspond the beta values 1 0 0 0 and 0 5 Default value is 1 0 Implicit Euler Timestep settings Y Newmark BDF Time stepping method Newmark C Implicit Euler Explicit Euler Crank Nicolson Newmark beta j For the BDF method only one of the predefined values 1 5 can be selected Timestep settings Time stepping method BDF Sky A A A Timesteps are defined by entering three numbers in the Timesteps field They have the following meaning values must be entered in this order e Step size
27. x Physical constants and parameters Gravity vector Physical constants direction o Stefan Boltzmann constant W m2K4 5 67e 008 Y direction 1 Z direction 0 Intensity m s2 9 82 Cancel Apply The default gravity value is 9 82 m s in the direction of the negative y axis 42 ELMER Front s User Guide 2 10 6 Equations Assigning equations for the bodies is perhaps the most important task in the problem setup in ELMER Front Each body must have an equation attached to it before any equation related data like material property sets body force sets initial and boundary condition sets can be entered for the body or its boundaries A typical equation definition sequence could be the following e A body or bodies are selected e An equation is defined a descriptive equation name is entered an equation type is selected parameters for the equation are entered e When all data is entered the new equation set is added to the list using the Add button e The defined equation set is attached to the selected body or bod ies using the Attach button Equations window is shown in Figure 2 14 Chapter 2 ELMER Front 43 Equations 1 Kettle 1 Kettle eq 1 Kettle eq 0 a M m m Figure 2 14 Equations window The name of the currently selected body is shown in the Body field This field is not editable The text
28. 11 Nodeld 3 1 o 1 Nodeld 4 1 1 0 Nodeld 5 1 1 1 Only vertices 1 and 3 will produce a boundary element Both the first and second vertices will produce a mesh density of 0 3 The last three vertices do not specify a density of their own 6 6 The edges Each edge record has the fields e Edgeld two positive integers a unique edge id and a boundary id e An optional mesh density field with an additional keyword N that may be used to specify a fixed number of boundary ele ments e The number of vertices that define the edge At least two e A list of vertex ids Example Edgeld 1 1 H 0 05 114 ELMER Front s User Guide 3123 Edgeld 2 2 N 10 213 Edgeld 3 3 214 Edgeld 4 3 245 Edgeld 5 3 235 The first edge is defined by three vertices and specifies a mesh density of 0 075 The second edge is defined by two endpoints and will be divided into 10 equal sized segments so there will be 11 nodes on that edge Because the node 3 didn t specify a mesh density of its own it will have a density that is the average of the densities of these two edges That is 0 155 6 7 The bodies Each body record has the fields Bodyld A unique body identification a positive integer An optional mesh density field e ElementOrder The order of the elements to be created for this body Either Linear or Parabolic Layers The number of layers in this body A list of layer records Each layer record ha
29. 3 5 4 5 5 Introductio gara a ee ELMER Front model file and user definitions Loading definition files The format 0 Ga A a A a ate a An example file 6 ELMER Mesh Generator input file format 6 1 6 2 6 3 6 4 6 5 6 6 6 7 Model description Mesh density control File structure A The header a The Vertices ci Et a A hed BE ao AAO Re eK The bodies 96 96 97 List of Figures iii List of Figures 1 1 1 2 1 3 1 4 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 2 10 2 11 2 12 2 13 2 14 2 15 2 16 2 17 2 18 2 19 2 20 2 21 2 22 2 23 2 24 2 25 2 26 2 27 ELMER Front 0 0 0202 ee eee 3 ELMER Solve 2 0020005 4 ELMER Poste lat ea Soe R A 5 ELMER workflow aaa a 6 Model fler aaeeea ia Se 11 ELMER Front main window 12 ELMER startup command under Microsoft Windows NT osa ass ra a Da Ss 17 File Men eo a ee Re Ps wa OA R A 19 Edit meni soroa eos A eke A k Ae eX 22 Bodies window 2 0 eee ee ee 23 Boundaries window 4 24 Settings window o e e 28 Problem meda 34 Model name and directories window 34 Datafiles window 36 Coordinate settings window 37 Timestep settings window 39 Equations wi
30. A keyword here Variable DOFS can be also entered in quotes This is safer for multiword keywords because an incorrectly written input like Variable DOFFs would not be interpreted as a Variable keyword with the value DOFFs 2 Instead it could be catched as an error Sound pressure is a complex valued variable so two degrees of freedom Variable DOFs 2 The autmatic labels would be P 1 and P 2 but it is possible to define a different label Now the labels in the Initial Condition and Boundary Condition panels will be Sound pressure 1 and Sound pressure 2 Label Sound pressure Panel Solver We add an extra field to the Helmholtz equation s solver parameters panel NOTE In practice this option is not useful for the Helmholtz eqution Chapter 5 ELMER Definitions File format 107 1 Field Bubbles Type Logical Initial Value True End Panel Sound medium is air so some proper default values 1 Panel Material The user wants to hide the density field completely so it is not displayed at all and the value is always the initial value 1 Field Density Hide 1 Initial Value 1 224 Field Sound Speed Initial Value 340 Field Damping Initial Value 0 End Panel Some special Initial Condition panel settings 1 Panel Initial Condition NOTE Field name is derived from the variable name and the degrees of freedom value the latter is used only if the variable ha
31. Chapter 2 ELMER Front 35 are used as arguments when calling external programs e Model name this name must be given because it is used as a part of the model file name whose default value is modelname emf e Problem name this optional name can be used for example to identify different versions of the basic model If given it will be part of the model file name modelname problemname emf e Model description this comment field is optional It is displayed only in this window e Problem description this comment field is optional It can be used to describe a specific version of the basic model It is displayed only in this window e Model directory the root directory for the model files e Include path A semicolon separated list of paths which are used as search directories when looking for parameter files Parameter file can be used in the following windows Initial conditions Body forces Material parameters and Boundary conditions e Results directory the root directory for the solver output files These simulation result files are stored using the following directory structure result directory MESHDIR meshname The default value for this directory is the model directory e Log directory The location for the log files created during the session the defaul value is model directory LOGDIR The directory browser button opens a browser window A for selecting directories Note Directory selection is done by single clicking
32. ELMER Front s User Guide ELMER Front s User Guide CSC Scientific Computing Ltd CSC Scientific Computing Ltd 2000 1st edition http www csc fi elmer No part of ELMER may be used reproduced stored or transmitted in any form or by any means without the written permission of CSC CSC assumes no responsibility or liability on any errors or inaccuracies in ELMER program or documentation Any kind of material dam ages or other indirect consequences resulting from any ELMER part documentation discrepancies and errors or non anticipated program behavior are limited to the value of appropriate products purchased from CSC ELMER products are delivered to the customer at the as it is state and revision level they are on the moment of purchasing and are declared in more detail in the ELMER license agreement User accepts and is obliged to follow the guidelines stated in the separate license agreement required in using any parts of ELMER This document is for informational use only All information and specifications given have been carefully prepared by the best efforts of CSC and are believed to be true and accurate as of time publishing CSC reserves the right to modify ELMER and its documents without notice Additional software product copyrights included in ELMER Sparse library copyright notice Copyright c 1985 86 87 88 by Kenneth S Kundert and the University of California Department of Electrical Engineeri
33. ER STOKES EQUATION M HEAT EQUATION Vv STRESS ANALYSIS To ADVECTION DIFFUSION EQ M When solving an equation attached to a body only those equation types are taken into account whose checkboxes are turned on When an inactive equation type is made again active all previously defined parameter values in the input area 2 are automatically taken into use Making an equation inactive may also affect other equations For example if the flow equation is turned off all flow related fields like Chapter 2 ELMER Front 45 convection are made inactive in other equations So it is a good idea to check all active equation types by using the equation type radio buttons whenever an equation is made active inactive by the checkboxes When the new equation set has been completely defined it can be added to the list of equation sets by pressing the Add button Pressing the Update button updates the currently active equation set definition The Delete button removes the currently active equation set from the listbox and also removes any attachments to bodies for this equation set 2 10 7 Attachment 1 Kettle 1 Kettle eq 2 Water 2 Water eq Bodies 1 An equation is attached to a body by first selecting the body in the bodies list Equation sets 2 Wiater eq 2 Next the equation is chosen 3 Finally the attachment is done using the Attach button under the bodies listbox An equation may b
34. Forces Body Force e Materials Material e Boundary Conditions Boundary Condition e Solver Settings Solver 102 ELMER Front s User Guide 5 4 5 Field properties The field properties are the following Add Absolute Box 1 If true an Abs check box is added to the right side of the field This property is meaningul only for a Browsable File field By default a browsed file name is stored with full path If this check box is visible in the panel and it is not checked only the file name is stored Default value is False Can Be Procedure 1 If true the Procedure check box in the panel is made active when the cursor is on the field This property is meaningul only for numeric entry fields Default value is True Can Be Table 1 If true the Table check box in the panel is made active when the cursor is on the field This property is meaningul only for numeric entry fields Default value is True Hide 1 If true the field is not displayed in the panel but it is still written to the sif file if a non blank Initial Value is defined Default value is False Index Type s Pre Post The variable name of an user defined equation can be used to index field names This means that the variable name can be part of the field name If the index type is set to Pre the field mames will be in the format VariableName FieldName If the index type is Post the format is FieldName Of VariableName For example
35. Front create a basis for numerical solution The model can be solved in ELMER Solver after saving the model file then by clicking the Solve button in ELMER Front ELMER Post is started from the Results button NOTE Notation from 1 to 4 in ELMER workflow is used as references later on in this manual Chapter 2 ELMER Front 7 Chapter 2 ELMER Front ELMER Front is the Graphical User Interface module for ELMER All essential problem solving definitions needed with other ELMER modules can be set in ELMER Front First part of this chapter sec tions 1 1 1 4 gives a general overview of ELMER Front The rest of the chapter explains in detail all menus and commands needed in a typical ELMER Front session 2 1 Input to ELMER Front When a new model is to be built in ELMER this starts by reading in the model geometry This geometry must be first designed with some external program ELMER Front can read the geometry from three different sources e CAD geometry a CAD file which has been created with an exter nal CAD program or by other applications e Mesh geometry a mesh file which has been generated either by ELMER Mesh generator or by other applications e Model file a file produced and saved during a previous ELMER Front session 2 1 1 CAD file A CAD file is an external file describing the model geometry in 2D wireframe format 8 ELMER Front s User Guide Supported CAD file formats are e unv Ideas neutral CAD
36. LMER Front 79 2 16 2 System info System environment info A x User name timo Computer mame fAVOSETT Machine he Operating system Windows T i Ss S SOS SSSCS OS version An Tel version Ba Tcl level Bani Tk version Bi o Tk level aai A is Tel library path C ELMER Pre 1 4 lib tcl8 1 Tk library path C ELMER Pre 1 4 ib tk81 Elmer Front version A Elmer Front script path C ELMER Pre 1 4 Front tcel SS Elmer Home CvELMERPrel4 0 S CO W OOOO Elmer Front Home C 2ELMER Pre 1 4 Front Working directory D WINNT Profiles Timo Desktop Figure 2 37 System info window The System info window displays some information on operation sys tem and on the external libraries which are needed for ELMER These are non editable information fields 2 16 3 About The About window displays information on the current ELMER ver sion 80 ELMER Front s User Guide About ELMER Front OO x ELMER Pre 1 4 6 ELMER Front 5 This is a front end program for setting boundary conditions and other parameters for CFD problems 2 17 Model window toolbar Draw Draw Draw Cad Mesh Sama 413 bodies surfaces J edges geometry geometry AIM Rotate Fx Toy TZ pales D Display Reset Figure 2 38 Model window toolbar The following toolbar buttons in the ELMER Front main window are used to control how the model geomet
37. ated only after the Update button is pressed The Delete button removes the currently selected entry from the listbox Each paramter must have a unique name In general it is better to use descriptive names for parameter sets However it is also possible to use the deafult automatic naming scheme where parameters are named like BodyForcel BodyForce2 If no parameter name is given or the name is given is this basic form the next available name in similar form is created automatically when the Add button is pressed This practice is not recommended but it be useful for quick experiments where the names are not essential If a target body or boundary does not currently have any parameter set attached to it a new parameter set is automatically attached to the target body or boundary when the parameter is added to the listbox Otherwise the user has to use the Attach button to attach the currently selected parameter to the currently selected body or boundary Only one parameter set can be selected at a time but in some cases it is possible to select multiple target bodies or boundaries for the parameter Multiple simultaneous selections are done by pressing the 16 ELMER Front s User Guide control key when selecting the targets with the left mouse button Pressing the shift key and the left mouse button while dragging with the mouse selects a continuous group of rows from the listbox When a parameter set is added to the lis
38. ation are needed in other equations during the simulation they are interpolated from one mesh to an other This is completely transparent to the user it is only necessary to define the mesh for each equation The Define mesh command in the Mesh menu opens a window where one can define all the meshes needed in the problem These meshes must have unique names These names are used also in the Solver settings window where the mesh for each equation is defined In the upper part of the window is a listbox where all currently de fined meshes are listed When a row in this listbox is selected the corresponding mesh is made active and its parameter definition can be checked or updated and the mesh can be generated or regenerated using the Generate mesh button at the bottom of the window When a new mesh is being defined the user has to first press the New mesh button This activates the mesh name field where one can now enter Chapter 2 ELMER Front 63 a new unique mesh name This new mesh is added to the mesh list when the mesh is generated The button and fields in the window are the following e New a name for a new mesh can be entered e Rename a new name for the currently selected mesh can be en tered e Delete the currently selected mesh is deleted e Display the currently selected mesh is displayed in the Model window e Mesh name the name for the selected mesh is displayed in this field and it is used for entering and renaming
39. buttons in the middle of the window are used to select the equation When a body is selected in the bodies listbox all boundary elements boundaries edges and vertices for the body are displayed in the boundaries listbox An asterix is again used to mark the boundary conditions which can be attached to the boundaries of the selected body Selecting a body displays only outer boundaries for this body These are boundaries which are not shared between bodies Boundaries bew teen two bodies are called inner boundaries and they are grouped un der body pairs A body pair inherits equation types from both parent bodies and body pairs are listed just like normal bodies in the bodies listbox Boundary elements can be grouped into boundaries faces in 3D and edges in 2D and into subelements like edges in 2D and vertices Nor mally boundary conditions are attached directly to boundaries but this can create conflicts at common vertices and at common edges in 3D if Dirichlet type conditions are applied For example if a temper ature constraint has different values in two boundaries which have a common vertex the final value at this vertex is not unique In ELMER Solver boundary conditions are applied in the order they are created in ELMER Front So this offers a simple method to control these conflicting values The last value will be used However it is sometimes important to control constraints at edges and vertices more exactly and for
40. created or used in ELMER during a model building and simulation session Chapter 2 ELMER Front 11 Abaqus Fidap Iges I deas I deas unv ELMER EME R Eon e Initial Conditions Boundary Conditions Material Parameters Solver Settings Model emf Meshdir Mesh parameters Mesh input file mif Viewfactors Gebhardtfactorts Mesh ELMER Mesh Solver input file Gebliardifactars Generator files rair zdat Solver output dat ep Restart files Figure 2 1 Model files 2 2 ELMER Front main window ELMER Front main window is shown in Figure 2 2 The numbers shown in brackets refer to different areas in the main window Window areas are the following e 1 Titlebar e 2 Menubar 12 ELMER Front s User Guide e 3 Model window toolbar e 4 Prcoess control toolbar e 5 Message area e 6 Status area 1 ELMER Front No model name Iof ES 2 File Edit Display Problem Model Mesh Solver Run Window Help E RAI l AIM Rotate TX Foy FZ gaa ena Display Reset elcome to using ELMER Front rev 5 Save 4 Results Process 5 1 q Info Equations None Timesteps None 6 Materials None Initial cond None Body forces None Outer be None Inner be None Meshes None Figure 2 2 ELMER Front main window The Model window toolbar 3 contains command buttons which control how the model geometry is displayed in th
41. ctory information field not editable e Result file solver output file the default value is modelname dat e Postprocessor file this file stores solver results in the ELMER Post format the default value is modelname ep e Restart file if this file is given ELMER Solver uses the variable values in this file as initial values This file should be in the output file format Chapter 2 ELMER Front 37 e Restart timestep position the timestep in the restart file which is used for the restart values A zero value in this field means that the last time step is used e Gebhardt factors file this file is used to store Gebhardt factors when they are calculated using the Gebhardt factors command in the Run menu Default value is GebhardtFactors dat e View factors file this file is used to store view factors when they are calculated using the View factors command in the Run menu Default value is ViewFactors dat Note Only simple file names can be entered in the file name fields because directory structure is already predefined by the result direc tory 2 10 3 Coordinate settings Coordinate settings OF E Coordinate system Cartesian 2D o Axi Symmetric C Cylindric Symmetric Polar 2D Cartesian 3D ae Polar 3D Coordinate mapping oe eee IO Cancel Apply Figure 2 12 Coordinate settings window 38 ELMER Front s User Guide Model s coordinate system is specifi
42. d properties which are not used in the sample file See the comments below Frequency is a model wide feature not related to a specific body or boundary so it must given as model level data NOTE This field could be added also to the Helmholtz solver s equation panel Panel Simulation Parameter Field Angular Frequency End Panel Some boundary related new fields 1 Panel Boundary Parameter This flag is used to calculate the sound energy at some interesting boundaries NOTE This routine is not available in the Helmholtz solver delivered with the system Here the user has made a special version for the equation 1 Field Compute Sound Energy Type Logical This serves only as an example of the Selection List field There is no use for this field in the Helmholtz equation 1 Field Sound Boundary Type Type String Widget Selection List Values Sommerfeld boundary Reflective boundary amp Pressure releasing boundary Other NOTE If no initial value is given for a selection list it would be the first list item 1 Initial Value Other End Panel 106 ELMER Front s User Guide A new equation is added Equation Helmholtz Solver Status Line Name Hlmz Process Table Name HH NOTE This is a user modified version of the Helmholtz solver Solver Procedure HelmholtzSolve2 HelmholtzSolver The name for the variable to be solved sound pressure Variable P NOTE
43. dynamic libraries needed for solving the equations must be defined elsewhere A basic structure in a definition file is an equation section In this section the user defines the name of the new equation the variable to be solved and the procedure the library and the function names for the equation An equation block can add a completely new equation or it can modify an existing equation However it should be noted that in general is not useful to add new fields to the predefined equations like Heat Equation because the existing predefined code for these Chapter 5 ELMER Definitions File format 97 equations would not use any of these new fields An equation definition contains normally also some panel sections where the new fields related to the equation are added to each rel evant panel Materials Initial Conditions etc When a panel section is within an equation section the field definitions will affect only the equation in question When a panel section is outside any equation section the field definitions will affect all equations For example a new material panel field would be added to all equations It is also possible to include other definition files within a definition file The include command must be outside any equation or panel sections 5 2 ELMER Front model file and user definitions When ELMER Front starts it creates an internal list of field defini tions which are related to the predefined equations menti
44. e 2 8 and they explained below in this order 1 Directory definitions Settings Al ES Values for user settings Model directory Cad files directory External mesh files directory Include path Results directory Log directory The default values for various model directories can be set and modi fied using these entry fields 2 Save Load control These parameters control various actions associated to the loading and saving of a model file e Apply model file settings forces the settings saved in a model file to be applied when the model file is loaded Otherwise these settings are ignored e Auto save external mesh in Elmer format forces the external mesh to be saved automatically in the Elmer mesh format when the corre sponding model file is saved 30 ELMER Front s User Guide Edit Apply model file settings lv Auto save external mesh in Elmer format lv Auto load mesh Vv Auto save model file Vv Auto save solver input file VV e Auto load mesh forces the possible mesh to be loaded always when a model file is loaded e Auto save model file forces the model file to be saved automatically when processes in the Run menu are started excluding ELMER Post This option is active only in the Power user level e Auto save solver input file controls whether the solver input file will be saved when a model file is saved This option is active only in the Power user le
45. e Model window This window is a separate graphics window for the model geometry and it is not shown in Figure 2 2 The Process control toolbar 4 can be used to start solver postprocessor and other processes The Chapter 2 ELMER Front 13 Message area 5 in the middle of the window is used for displaying short messages related to commands and actions made during the session The Status area 6 at the bottom of the window tells the number of currently defined parameters and other status information for the model In the example model parameters have not yet been defined as the None values indicate 2 3 General user interface features This section gives an overview of the features which are common for all ELMER Front windows 2 3 1 Standard window buttons The window control buttons located at the bottom of each ELMER Front window have the following functions Cancel Apply e Ok accepts if syntax is correct and saves all possible changes made in the window Note however that you still have to save the model file separately before changes are stored permanently The win dow is closed e Cancel abandons all possible changes made in the window and closes the window e Apply same as the Ok button but the window is left open In general windows will remain open until closed by the user with the Ok or Cancel buttons Using the commands in the Window menu all open ELMER Front windows can be controlled in group
46. e attached to a single body or multiple bodies There are no restrictions how bodies and equations are attached to each other but when the attachement is done the body inherits a 46 ELMER Front s User Guide kind of equation mask from the equation This mask is transparent to the user but it controls how other properties can be attached to this body or its boundaries For example if no flow equation is defined for a body it is not possible to attach any flow related material properties for this body in the material properties panel 2 10 8 Advection diffusion equation Equation Variables A x ADVECTION DIFFUSION variables Enter one variable name per line max 8 variables Oxygen Carb or j Equations Ox coma os C Navier Stokes Heatequation Stress analysis E JAdvection Diffusion Clear all Clear panel Clear entry Variables Advection Diffusion settings NAVIER STOKES EQUATION I Convection Oxygen Diffusion I HEAT EQUATION Vv None Carbon Diffusion I STRESS ANALYSIS r Constant ADVECTION DiFFUusIONED _ 9 Computed Figure 2 15 Advection diffusion equation When the advection diffusion equation is activated by checking the cor responding checkbox a separate window for advection diffusion vari ables is opened In this window the user may enter or update the variable names for which the advection diffusion equation should be solved These variable names are displa
47. e can be multiple panel sections Panel s Panel name s is needed Field s Field name s is needed NOTE This is a list of all possible field propereties in the panel section To see the role of each property and the default values see the field property explanations below Add Absolute Box 1 Can Be Procedure 1 Can Be Table 1 Hide 1 Index Type s Pre Post Initial Value s r i 1 Label s Label By Coordinate 1 Label Width i Subpanel i Type s String File Real Integer Logical Chapter 5 ELMER Definitions File format 101 Unit Label s Values list of values Widget s Entry Check Box Browsable File Selection List Widget Width i Field s A new field starts End Field NOTE End Field is optional End Panel End Panel is needed 5 4 3 The Include section An include section must be outside any equation and panel sections Include s Path s for the include file 5 4 4 Panel names The panels where new fields can be added are predefined and they are identified in the definition file by the names used in the ELMER Front menus An alternative name is given in parenthesis it is the name used in the sif file when applicable e Model Parameters Model Parameter e Simulation Parameters Simulation e Physical Constants Constant e Equations Equation e Body Parameters Body Parameter e Boundary Parameters Boundary Parameter e Initial Conditions Initial Condition e Body
48. earched using the Include path value given in the Model name and directories window Otherwise the path given in the entry field is used when searching the file Note that the existence of the file is not checked when the data is entered in ELMER Front If the initial condition set contains also other data fields values in these fields will always overwrite corresponding values in the parameter file data Paramter files can be used also for body forces material properties and boundary conditions Procedure entry e Proc checkbox clicking this checkbox opens a separete window for procedure definition This window is shown in Figure 2 11 4 and the fields in the window are the following Model Initial conditions Clear ai Clear pane Clear erty Edit Y Proc Table Navier Stokes initial conditions Velocity R m s 10 Procedure definition for YELOCITY_1 iof x Velocity 2 m s 0 Output librar II Velocity P m s Pressure Pa 100000 Function name Variable none Source file Compiler 30 exe dll I C 1ELMER Pre 1 Libraries fe 1ELMER Pre 1 41libisolver li Edit source Compile source OK Cancel Apply e Output library the library where the procedure being defined is Chapter 2 ELMER Front 55 stored e Function name the call name for the procedure in the library e Variable the possible argument variable can be selected by press ing this bu
49. ed in the Model window these selections are reflected in the object listboxes in data entry panels On the other hand selections made in these panels are highlighted in the Model window In the following example a boundary has been selected in the Model Window by double clicking on it As are result the correponding boundary the parent body and the attached boundary condition set rows are displayed as selected in the Boundary conditions window 82 ELMER Front s User Guide l ES Bodies Boundaries Boundary condition sets 2 1 Steel stf 2 Kettle bottom 3 Kettle symmetr 4 Kettle W ater 5 Water Surface 6 Water smtr Boundary conditions x 0 12 Mesh Meshi ELMER Front Boiler 0 07 La Lel Figure 2 39 Model window example The model can be manipulated in the window either by dragging it with the mouse or using the arrow buttons in the main window Drag ging with the left mouse button moves the model in the window Drag ging with the right mouse button rotates the model The model can be scaled zoomed with the middle mouse button or pressing left and right buttons simultaneously when using a 2 button mouse Bodies are displayed using different colors These colors can be defined using the the Bodies command in the Edit menu All body elements inner and outer boundaries edges and vertices are uniquely numbered Same numbers are also used to identify these elements in the data entr
50. ed in this window which is opened with the Coordinate settings command Available coordinate systems depend on the dimension of the model geometry In 2D possible options are e Cartesian 2D e Axisymmetric e Cylindric symmetric e Polar 2D In 3D options are e Cartesian 3D e Cylindric e Polar 3D Coordinate Mapping Coordinate dependent variables like velocity are entered in data windows by components like velocity X velocity Y velocity Z The default mapping between the components and the coordinate axes is X 1 Y 2 and Z 3 This mapping can be changed entering a new index set in the Coordinate mapping fields The field labels for the entries are also altered when coordinate system is changed e Cartesian X Y Z e Cylindric R ho Z P hi e Polar R ho T heta P hi These labels are also used in data entry windows to illustrate the coordinate system and the mapping currently in use Chapter 2 ELMER Front 39 2 10 4 Timestep settings Timestep settings A x Tinestept_ Name framescepa A so Delete Figure 2 13 Timestep settings window The Timestep settings window is used to set the time dependency and timestep settings for the simulation Active set button selection list of the currently stored timestep sets The name of the currently active set is displayed as the button label Name a user given name for the current timestep set The Add Update and Delete buttons are
51. ed to control how the parameter values set in this window are used e Save for session current settings apply only in this session e Save in model settings are saved when applicable in the current model file e Save in file settings are saved in the current settings file 2 9 Display menu Display menu is used to control the Model graphics window 32 ELMER Front s User Guide 2 9 1 Display model The Display model command can be used to open the Model window if it is not visible This command is also Display model attached to the Display button in the Reset Ctrl P main window Display Labels Ctrl L The model is displayed in a separate graphics window For details see the Bodies Ctrl B Model window section in this chapter 2 9 2 Reset The Reset command sets the Model window into its initial state 2 9 3 Labels Display Labels ojx MV Boundary All J Vertex None Cancel All body elements inner and outer boundaries edges and vertices are uniquely numbered These numbers can be displayed as element labels in the Model window These same numbers are also used to identify the elements in the data entry windows The Labels command opens a window where the lable display can be controlled In a complex model it is sometimes desirable to turn the labels off by unchecking the corresponding checkboxes The All and None buttons control these labels in groups Chapter 2 ELMER Front
52. eir relative order is important Only the currently active equation types are displayed in this window The default solving order is the following 1 Heat equation 48 ELMER Front s User Guide 2 Navier Stokes 3 Stress analysis 4 KE Turbulence 5 Advection diffusion equations a separate equation for each advection diffusion variable 2 11 Model menu After all body equations and other general problem data have been entered the model parameters are entered This is done using the model menu commands Figure 2 16 shows the Model menu where also the body list submenu has been opened Clicking the dotted line on the top of this submenu opens a separate body list window on the desktop Model info Body info iO dy list Initial conditions Body forces Materials Boundary conditions Figure 2 16 Model menu 2 11 1 Model info The Model info command opens a window displaying general model information Most of the fields are non editable information fields but the following fields are editable e CAD input file the name of the original CAD source file e Mesh input file the name of the external mesh input file e Model created model creation info Chapter 2 ELMER Front 49 Values for these fields are set automatically when a model is created They can be updated to reflect possible changes in the external file names but it is not necessary because these values are not used for
53. er coordinate values per row In this case the table must be ended with the End keyword See the example file below keyword for the data type in the table coordinate values Integers il i2 are given only if the keyword Variable Index is given for an indexing argument variable see above this keyword which is needed when only one size parameter is given Note Vertices are always given as a table of points Vertex coordinates can be either 2D or 3D coordinates The number of coordinates must always be given using the Size keyword If an index variable is given in the beginning of each table row this value is used as the vertex id Index values should be unique and the index variable an argument variable in general is not included in the size parameter The number of values per data row should refer only to the actual data values Chapter 3 ELMER Geometry File format 89 If no index variable is used vertices are implicitely numbered using integers starting from one 3 2 3 The Edge section Edge i the unique id number i must be given Name s optional a string Geometry s optional a string values are Linear Circle Center r optional two or three real coordinate values defining the center of a circle Radius r optional a real value for the circle radius Vertices i vertex indices defining either a line can be a polyline or an circular arc End Note a full circle can be defined by given the center and
54. ere is no way to turn it off 1 Hide True End Panel End Equation An optional end of file keyword 1 End File 110 ELMER Front s User Guide Chapter 6 ELMER Mesh Generator input file format 6 1 Model description The input model consists of a number of bodies that are divided into layers The mesh type can be selected separately for each layer The layers are represented as collections of closed loops of edges One outer boundary loop and possibly several inner cavity loops The edges are defined by lists of nodes that define a broken line segment Each loop is a sequence of directed edges The edges are directed so that the defined layer is on the left side of the edges So the outer loop goes counterclockwise around the layer and the inner loops clockwise around the cavities Adjacent edges in a loop must share a common node so that the last node in an edge is the same as the first node in the next one The first node of the first edge must be the same as the last node of the last edge The nodes corresponding to the geometry vertices will have the same ids that the vertices have in the input file Predetermined inner nodes can also be specified 6 2 Mesh density control The mesh density is defined by a h value that is the preferred element side length The density values can be described at any level of the Chapter 6 ELMER Mesh Generator input file format 111 model hierarchy A density value can be given f
55. ermined node at position 0 5 0 5 The edge 2 has a negative sign so the nodes of the edge are Chapter 6 ELMER Mesh Generator input file format 117 taken in a reverse order Thus this body is a single triangle formed by nodes 1 2 and 3 The triangulation will start a the middle of edge 2 The mesh density is controlled by a cartesian grid The type dependent fields in a layer of type QuadGrid TriangleNE Grid TriangleN WGrid TriangleUJNEGrid TriangleUJNWGrid Tri angleFBNEGrid or TriangleFBNWGrid are e GridSize The number of elements in which to split the odd and even edges of the layer Two positive integers If this field is omitted the edges are split as defined by the density values The values given in a GridSize field override any density values given for the edges Example Bodyld 2 ElementOrder Linear Layers 1 Layerld 1 R 0 5 LayerType QuadGrid GridSize 5 10 Loops 1 Loopld 1 Direction 1 Edges 4 4 523 This body will be a grid of 50 quadrilateral elements The outer loop is given clockwise but the direction field tells the program to interpret it backwards Another way to specify the grid size could be to give N 5 to edges 3 and 5 and N 10 to edges 2 and 4
56. erved for the equation list 104 ELMER Front s User Guide Type s String File Real Integer Logical Field s data type Default is Real Unit Label s This label is added after the field label No default value Values list of values A list of values in the format First Second Third value NOTE The braces must be entered This property is meaningful only for a Selection List field No default value Widget s Entry Check Box Browsable File Selection List The widget type of the field in the panel Browsable File is an entry field with a file browser button its default data type is File Selection List is a drop down menu for a list of predefined values Default widget type is Entry but for a logical field the default type is Check Box Widget Width i Widget s width in the panel measured as characters Default value for an Entry field is 12 and for a Browsable File field it is 15 5 5 An example file The following example file is a modified version of the sample definition file which is delivered with the ELMER package samples other_ files front edf The sample file defines all fields needed for the Helmholtz solver This equation is an example of a user defined equation and it ie the dynamic library is also delivered with the ELMER package The modifications here are quite artificial and they are made only to Chapter 5 ELMER Definitions File format 105 illustrate some fiel
57. ethod based program frame which can be applied and further developed by academic and indus trial communities in research and development and in education ELMER development was initialized in the Finnish national compu tational fluid dynamics CFD technology programme in 1995 1999 funded by Tekes the Finnish technology agency At the first stage the most active collaborators were CSC responsible organization in ELMER development Helsinki University of Technology Jyv skyl University Okmetic Ltd and Technical Research Centre of Finland and the main application areas were closely related to semiconductor and paper machine industries Currently CSC continues its coordinative role in ELMER develop ment Development is in active phase and new application areas are continuously founded These include for instance micro electro me chanical systems MEMS simulation of blood flow casting problems and crystal growth in magnetic fields Some parts of ELMER have even utilized in CAVE environment 1 1 ELMER Capabilities Since its creation ELMER has progress from the ordinary CFD pro gram towards a computational tool which can tackle multi physics problems ELMER solves problems like 2 ELMER Front s User Guide e compressible and incompressible fluid flows e non Newtonian flows e laminar and turbulent flows e heat transfer by conduction convection and radiation e phase changes e free surfaces e stresses and displaceme
58. ew 5 Figure 1 3 ELMER Post Besides large variety of modeling computing and visualization tools ELMER also offers some special features which may help in research work These include among others e interfaces to IDEAS ABAQUS and FLUENT e MathC language for analyzing numerical results in ELMER Post e computation of view factors and Gebhardt factors modeling of radiation 6 ELMER Front s User Guide 1 3 ELMER Work flow The user can start ELMER software by clicking the ELMER icon on the computer s desktop or writing the starting command on the command line Then ELMER work flow proceeds as shown in Figure 1 4 Real Geometry A E i a Assembly 1 ELMER Front Circleinbox mam roy an Hep Ele Edi Display Problem j gt a Problem Misal Model name and file Li p cs ie h oe SA in Mesh parameters SEE Mathematical Figure 1 4 ELMER workflow e As ELMER has been started ELMER Front opens User can now read in the file containing the model geometry 1 and start operating with the model shown on a separate Model window 2 e After all definitions mathematical equations mesh and material parameters have been made ELMER Solver can be started 3 e Solver output is used in ELMER Post visualization and results analysis 4 Workflow from 1 to 4 represents necessary optional steps during a typical user session Definitions in ELMER
59. f KS i Kf K K se PER im zs Sl y S L R Ki fi f oi S ra Ea i a x Yi BE be KK E KBE KT IS KIS O SSN IE is See RS SOS sents i Be PE eS pa WASPS POR E ns KI a KARAM is ay El M EXE P ss oe RS aS HAS NA ree BE one ieee icy i E PATAN ANASANAT ATAT AN ANAN PATAYAN ATAV AAY 0 KI S at A A E kf KS Ky if is if ss cf Ss K us Ky Sy ra soe PRS EE AY ADA se E KE E sf ws AE Ky 1 fs Se ay Kr A MAVA YATAYAYATANAYATATATAYATA iy kf Si se ise S Do OOO O OOOO Y Y K Y SL k E ow DAS vs i Ki KT SAA PPO ORICA va a Va VAAS AS AAA AYA A ST a RARE SARRIA ATA ATATA TA TA TA TA TA TA VAYAS O SS T ATATA TAN TANITASAIT OS ALR arar ECARAAEREREBRARIARA RI A Figure 1 1 ELMER Front ELMER Solver processes mathematical models into discrete form handles coupled systems nonlinearities and time dependencies and provides output data for ELMER Post 4 ELMER Front s User Guide 1 0 9691E 09 1 0 9691E 09 Figure 1 2 ELMER Solve The function of ELMER Post is to visualize the numerical results produced by the solver ELMER Post operates with the unknown variables and shows contours vector fields animations etc on the screen It can also manipulate computed data into another form for instance heat fluxes from temperature distributions Chapter 1 Overvi
60. f control key is pressed instead of the shift key mesh elements can be selected by clicking them with the left mouse button Using the right mouse button cancels the current selections 2 Second method at first a reference mesh element is selected using the mouse This base selection can then be extended by using the Select button in the window The extended selection is controlled by the criteria set in the Selection radio button group These criteria are the following 26 ELMER Front s User Guide e By neighbor selection is extended by adding neighbor elements for currently selected elements Neighbor elements are added only if their normal vector changes less than what is set by the Normal tolerance slider e By normal select all elements whose normal vectors differs less than the given tolerance from the normal vector of the reference ele ment e By plane select all elements which are on the same plane as the reference element Plane distance can differ within the tolerance which is set by the Distance tolerance slider e All select all mesh elements in the boundary 2 8 4 Selection mode Selection mode controls how the element selec tion actually behaves Selection mode e Extend always extends the current selec tion Extend Ea e Reduce always reduces deselects the cur woe rent selection E Ti gale e Toggle toggle the selection state for the elements being effected Value displayed in t
61. file format e igs Iges file format e egf Elmer Geometry File format A text file format for creating basic 2D geometries For more detailed description see Appendix 3 Overview After a CAD file has been read in ELMER Front creates internally a boundary representation from the input geometry A CAD model contains typically multiple parts called bodies The geometry input file should describe all the bodies called also objects or materials which are needed in the problem In 2D bodies are defined by edge loops These loops should be closed and not intersecting with themselves or with any other edge loops In 3D bodies are defined by surfaces surface patches and restric tions are similar as in 2D Surfaces are described by edge loops and again equivalent restrictions hold as for bodies in 2D However cur rently only 2D CAD geometries are supported This is because current ELMER Mesh generator is restricted to 2D geometry Geometry definitions When defining a CAD geometry the following restrictions should be taken into account e No change in the geometry is allowed after the external CAD ge ometry is read in This means that bodies or boundaries cannot be split or combined e Because boundaries cannot be split a boundary segment defined by corner vertices is the lowest level where boundary conditions can be set e Because boundaries cannot be recombined a large number of bound ary segments results in a long li
62. for an equation does not converge or converges slowly and in these cases it is a good idea to test with different parameter values Fields in the window are grouped so that fields related to the general form and linearization methods of the equation are in the left side of the window Fields related to the linear system and its solving methods are on the right side of the window STABILIZATION when selected solver uses stabilization It is a recommended option for the Navier Stokes equation LUMPED MASS MATRIX the matrix corresponding to the mass matrix is lumped in the equation LINEARIZATION e Max iterations linearization is based on subiterations and this number sets the maximum number for these iterations e Tolerance if the linearization error norm is smaller than this num ber linearization iteration is stopped e Relaxation factor default value is 1 0 Linearization could be speeded up in some cases using somewhat larger value On the other hand sometimes a value less than unity is needed to get any solution Use Newton when selected Newton s linearization method is used It is faster than the default method Picard but is useful only when the actual solution is close enough to the exact one The following fields control when Newton s method is started e Newton after iteration Chapter 2 ELMER Front 71 e Newton after tolerance Newton s method is not started until at least one of these criteria is fulfilled
63. he Next active field tells the next tolerance value which would select new mesh elements 2 8 5 Remove CAD geometry Mesh boundaries cannot be mod ified if model geometry is defined by a CAD geometry This limi Remove Cad geometry tation is implemented to prevent Remove inactive paramter data conflicts between the CAD and mesh geometries However if the original CAD geometry is removed from the model the existing mesh can be modified as it were a normal external mesh The original CAD geometry is removed from the model using the Re move Cad geometry command Note that remeshing is not possible if the CAD geometry is removed It is also not possible to restore the CAD geometry so it is recommended to save the original model and save the mesh only version in a different model file Chapter 2 ELMER Front 27 2 8 6 Remove inactive parameter data An equation may be inactivated in the model However the parame ters related to this equation are not erased by this They just become idle and they will be reactivated if the equation is again turned on This command removes these nonactive parameters permanently from the model file 2 8 7 Solver input file An existing solver input file is opened for editing with the Solver input file command However a two requirements has first to be met Solver input file 1 User level has to be set to Power user See User level menu below 2 The Auto save solver input
64. his means that element size can change freely over the body On the other hand quadrilateral meshes are always structured This means that a quadrilateral mesh can be defined only for those bodies which are quadrilaterals ie for bodies which have four boundaries These boundaries can be polylines which consit of multiple segments but topologically they must define a quadrilateral geometry Triangular meshing is controlled by the mesh density values which are defined at body vertices During the triangulation process these densities are interpolated over the body and these values control the mesh density in different parts of the body The final structure of the mesh may depend on the actual meshing method but the basic principle is the same When defining the mesh it is possible to enter these density values for each vertex in the model However for convenience data entry is organized so that density values can be entered either at model body boundary or vertex level whatever is suitable for the problem Whenever a lower level value is not defined it is inherited from the upper level So it is possible to enter just one model level density parameter and create a constant density mesh for the whole model In a structured mesh opposing boundaries are always devided into same number of mesh segments mesh boundary elements The struc ture is thus defined by two numbers which tell the number of elements per boundary pairs It is possible
65. ily with the GridSize specification described below e TriangleNEGrid TriangleNWGrid TriangleUJNEGrid TriangleUJNWGrid TriangleF BNEGrid or TriangleFB NWGrid A QuadGrid that is split into triangles NE NW specifies the splitting direction of the first quadrilateral UJ means an alternating direction and FB is a sceme that alter nates only along the first and third edges The type dependent fields in a layer of type VoronoiVertex Mov ingFront SSSFMovingFront or SSMFMovingFront 116 ELMER Front s User Guide e FixedNodes The number of fixed mesh nodes and a list of vertex records e BGMesh Background mesh type One of Delaunay Grid SparseGrid DenseGrid or Explicit e If background mesh is Explicit Background mesh size and a list of nodes with two coordinates and a mesh density value The other selections require no addi tional parameters If the type is SSSFMovingFront of SSMFMovingFront the following additional fields e Seed Seed type Implicit or Explicit If type is Explicit Nodes Three node ids that define the initial front If type is Implicit Edge An edge id A segment from the middle of the edge is used a the initial front Example Bodyld 1 ElementOrder Linear Layers 1 Layerld 1 R 0 5 LayerType SSSFMovingFront FixedNodes 1 NodeId 4 1 0 5 0 5 BGMesh Grid Seed Implicit Edge 2 Loops 1 Loopld 1 Direction 1 Edges 2 1 2 This will create a mesh with one predet
66. in a browser window Chapter 2 ELMER Front 21 e Browse solver input file displays the solver input file in a browser window Note Although model file is a nor mal text file it is not meant to be a edited off line The internal file Browse solver input file structure is strictly predefined and any outside changes could make it unreadable for ELMER Front 2 7 5 Save mesh Save mesh in Elmer forn Save mesh in Elme Exit By default an external mesh is saved as an ELMER mesh when the model is saved Save mesh in ELMER format command can be used to save the ex ternal mesh explicitly if this default behavior is turned off Save mesh in ELMER Post format command saves the mesh in the ELMER postprocessor format 2 7 6 Exit Exit command ends the current ELMER session If there is any un saved data the user is given an option to save the model before closing the program 22 ELMER Front s User Guide 2 8 Edit menu Bodies Boundaries Remove Cad geometry Remove inactive paramter data Solver input file Working directory User level gt Settings Figure 2 5 Edit menu 2 8 1 Bodies Bodies command opens a window where body names and colors can be defined This window is shown in Figure 2 6 Default body names are in the form BodyN where N is a sequence number Because body names are used in the windows where data related to the bod
67. ity value The input file is divided into 4 major fields e A header e A list of vertices e A list of edges e A list of bodies 112 ELMER Front s User Guide There can be lines of comment between these fields Comment lines begin with an or a 4 The vertex list is only ment for the vertices used for defining edges The additional inner nodes are listed in the layer records 6 4 The header The header starts with the keyword Geometry2D followed by 5 mandatory fields e H The global mesh density value e MeshScalingFactor The mesh scaling factor All mesh den sity values are multiplied by this value e Nodes The number of vertex records Edges The number of edge records e Bodies The number of body records Example Geometry2D H 0 1 MeshScalingFactor 1 5 Nodes 3 Edges 2 Bodies 1 All the density values in this file will be multiplied with 1 5 including the 0 1 given in the header The mesh scaling factor is an easy way to change the overall density of the entire mesh 6 5 The vertices Each vertex record has the fields e Nodeld Two positive integers a unique vertex id and a bound ary id If a boundary element is not required at this vertex a zero or negative boundary id may be given Chapter 6 ELMER Mesh Generator input file format 113 e An optional mesh density field See above e Two vertex coordinates Example Nodeld 1 1 R 2 0 00 Nodeld 2 1 H 0 2
68. les TextPad TXTPAD32 EXE The following browse mode flags are available Logfile ouput is directed to a logfile Shell output goes to system console None no output at all 1 Browse Mode Gebhardt Factors String None Browse Mode Mesh String Shell Browse Mode Procedure Compiler String Logfile Browse Mode Solver String Logfile Browse Mode View Factors String Logfile 96 ELMER Front s User Guide Chapter 5 ELMER Definitions File format 5 1 Introduction This appendix describes the ELMER Definitions File format By default ELMER Front supports only a set of predefined equations Navier Stokes KE Turbulence Heat Equation Stress Ananlysis and Advection Diffusion Equation This means that the data entry panels contain only fields for these equations Using a definition file the user can define new panel fields and modify the properties of the existing fields When a definition file is loaded into ELMER Front the new user defined equations behave practically similarily as the predefined equations However there is one limita tion There is no mechanism to define procedures for checking the data integrity The normal data checking checking entry values for numeric fields etc is automatically in use but a more complicated cross checking is not possible for the user defined fields It should be also noted that the definition file is only meant to create the user interface for the new equations Any procedures
69. llowing functions Attach Detach Add Delete e Add adds a new parameter defined with the values in the data entry fields to the list of parameter sets e Update updates the currently active parameter with the values in the data entry fields Chapter 2 ELMER Front 17 e Delete deletes the selected parameter from the list and detaches the parameter from all the bodies or boundaries it is possibly attached to e Attach attaches the currently selected parameter to the currently selected body or boundary e Detach removes the current attachment from the currently se lected body 2 4 Starting ELMER Front ELMER Front starts by the ELMER command This command can be given in the command line or by using desktop menus or icons if they are available in the platform where ELMER is used Run 21 x Type the name of a program folder or document and Windows will open it for you Open X M Runin Seperate Memon Space Cancel Browse Figure 2 3 ELMER startup command under Microsoft Windows NT The following optional parameters may be used when the program is started e model directory model directory name e model name model name e problem name problem name e settings file settings file name e definitions file definitions file name e results directory results directory name e include path include path definition 18 ELMER Front s User Guide e log directory log directory
70. loaded at the start time by using the command line argument e definitions file definitions file name A definition file can be loaded also during the ELMER Front session with the Load definition file command in the File menu Definition files are searched and loaded in the above order and any later definition overwrites a possible previous definition 5 4 The format The basic structure of a definition file is as follows Equation equation name equation properties Panel panel name Field name field properties End Panel End Equation Include path Panel panel name Field name field properties End Panel In the following format description one of the letters s r i 1 after a keyword means that some data value is needed in that place and the type of this data should be a string real integer or logical Chapter 5 ELMER Definitions File format 99 A string value should be given in quotes if it contains spaces Quotes within quotes are not allowed A logical value should True or 1 or False or 0 On each line all characters after P or are interpreted as com ments Lines can be continued by entering or amp as the last non blank character in the line Any leading white space is removed from the input line before it is added to the line being continued 5 4 1 The Equation section An equation definition is always a separate section it cannot be inside any other section
71. me refering to a definition file The name for a definition file can be specified also in the command line when ELMER Front is started as explained in the previous section Definition files are searched and loaded in the above order and any later definition overwrites previous definitions Chapter 2 ELMER Front 19 The structure and the contents of the definition file is described in Appendix 5 2 7 File menu File menu commands are used for opening saving and browsing the model data and related files These commands are shown in Figure 2 7 ELMER Front No model name MES Edit Display Problem Model Mesh S Dpen Cad file Open mesh file Open model file Load mesh tH Unload mesh Save model file tri Save model file As Browse model file Browse solver input file Save mesh in Elmer format Save mesh in ElmerPost format Exit Alt Figure 2 4 File menu 2 7 1 Opening commands A new or an existing model is opened using the following commands e Open CAD file read model geometry from an external CAD file e Open mesh file read model geometry and mesh from an external mesh file e Open model file read a previously saved model file emf file 20 ELMER Front s User Guide If a model was previously opened and there is some unsaved data an option is given to save the old model before loading a new one 2 7 2 Load Unload Mesh Mesh can be loaded or unloaded during
72. n alpha value 0 255 92 ELMER Front s User Guide Edges 34 56 defined by four edges 3 and 4 are polylines End Body 2 body number two is the water in the kettle Name Water Color 0 0 255 255 Edges 1 2 3 three is the minimal number of edges in 2D End Chapter 4 ELMER Front settings file format 93 Chapter 4 ELMER Front settings file format When an ELMER Front session is started values for various control variables can be initialized from an input file This appendix describes the structure of this file and the keywords which are available for setting initial values to these variables All keywords given in the file should be within a single section called User Settings So the basic structure for the file is the following User Settings Keyword value Keyword value End The order of the keywords is free In the following all keywords start ing with Default are keywords whose values can be stored only in a settings file Other keyword values can be stored also in a model file and they will be used automatically when the model file is loaded However the user can prevent this by defining the settings parameter Default Use Model Settings to be false This can be done either in a settings file or by using the Settings command in the Edit menu bi On each line characters after or are interpreted as comments A string value must be given in quotes if it contains spaces or if
73. nditions Al ES Bodies Initial condition sets 1 Kettle 1 Kettle init E 1 Kettle init 2 Water 2 Water init 15M 25M Navier Stokes Heat equation 3 Velocity F m s 0 Welocity 2 m s 0 4 Welocity P m s Pressure Pa 100000 Figure 2 20 Parameter selection example Bodies can be selected also in the Model window by double clicking on the body area As a body is selected all those initial condition sets which can be attached to the body are marked with an asterisk Any of the conditions marked with an asterisk matches the equation type of the currently selected body and consequently they can be attched to the body In the example the Water init condition set matches the Wa ter body Parameter file field An initial condition set can also contain a parameter file name Name for this file is entered in the Parameter file field This field can be activated by checking the File checkbox at the right side of the field Unchecking the checkbox makes this field inactive and its value is not taken into acoount When ELMER Solver sees a parameter file name entry in the solver 54 ELMER Front s User Guide input file it reads input values for this parameter set from the given file The structure of this file should be the same as in the standard solver input file If the parameter file name does not contain any path information i e when it is a simple file name the file is s
74. ndow 5 8 43 Advection diffusion equation 46 Model menu 2 2 ee 48 Body forces window 4 50 Materials window 04 51 Initial conditions window 52 Parameter selection example 53 Argument variable list 55 Boundary conditions window 57 Mesh element types 60 Mesh example 61 Define mesh window 0 25 62 Mesh structure window 64 Mesh density window 67 2 28 2 29 2 30 2 31 2 32 2 33 2 34 2 35 2 36 2 37 2 38 2 39 2 40 ELMER Front s User Guide Mesh logfile example o o 68 Solver settings window 69 Advection diffusion solver example 70 Processor settings window 72 RUI MEL a at EA a oe ee ed 73 Process table o 76 Window list example 77 Help Mea o ee bbs Ae Bak Be Bee id aint 78 Graphics info window 4 78 System info window 22 79 Model window toolbar 80 Model window example 82 Statistarear ance ek See Ee oi eae SE a ee ERA 84 Chapter 1 Overview 1 Chapter 1 Overview ELMER software development is a joint project between Finnish uni versities research laboratories and industrial companies The main objective is to create a finite element m
75. ng and Computer Sciences University of California Berkeley California 94720 About this Manual The intended audience for the User Guides of ELMER are engineers and scientists in universities research institutes and industry The documents aim at offering a detailed approach to the use of ELMER software For the first time user having basic knowledge on mathe matical modeling numerical methods and computer science it acts as a start up Experienced users can utilize the User Guides in problem solving teaching and training ELMER Front s User Guide provides information on ELMER graph ical user interface It leads the user to create mathematical models and control existing numerical and visualization tools The present ELMER User s Guide corresponds to ELMER software version 1 4 for Windows NT and Unix platforms ELMER Front s User Guide will be delivered via the World Wide Web Latest documentations and program versions of ELMER are available at http www csc fi elmer ELMER Installation ELMER software is delivered on CD ROM with the installation in structions After inserting the CD ROM into the computer the ELMER software will be automatically installed by the auto install program As user receives a new ELMER version update all user applications must be carefully checked against any discrepancies between old and new versions The software provider does not guarantee congruent results between different versions
76. nsion of the data e Size 2 if the parameter is not a scalar this is the second dimension of the data For a scalar field like density these values are always one Argument variables are always scalars e Entry field the data in the table is entered using this field First value should be always for the argument variable if it is defined After that come the data values The number of data values should be Sizel x Size2 and these values should be separated by spaces e Add a new row is added at the end of the table e Insert a new row is added above the currently selected row e Update updates the currently selected row Chapter 2 ELMER Front 57 e Delete deletes the currently selected rows e Line nbrs when this checkbutton is checked a line number is dis played at left side of each row 2 11 5 Boundary conditions The Boundary conditions window differs from the previous windows as boundary conditions are applied to boundaries and other elements defining the bodies like edges and vertices Thus in addition to the bodies and boundary conditions listboxes this window contains a third listbox the boundaries listbox Boundary conditions ES 3 Inner 4 Kettle Water 1 2 Kettle Water 4 Kettle Water Figure 2 22 Boundary conditions window 58 ELMER Front s User Guide Entry fields are grouped by the equation type also in this window If the problem contains more than one equation type the radio
77. nts in elastic bodies e vibration e magnetohydrodynamics e fluid structure interactions The open design of ELMER allows user to work on a simulation on a desktop on small scale before performing the full simulation on an appropriate machine ELMER has e open and flexible structure for user application development e scalability to various computing platforms and operating system e flexible and fast re simulation with temporary values 1 2 ELMER Structure ELMER is a collection of programs rather than a single monolithic application It consists of e ELMER Front preprocessor e ELMER Solver solver based on finite elements e ELMER Post postprocessor ELMER modules can be used as an integrated process or indepen dently The structure of ELMER is divided into three components The first part ELMER Front is a tool for initializing the computa tional process in ELMER see Figure 1 1 ELMER Front generates finite element meshes allows user to build mathematical models graph ically and finally produces input data for ELMER Solver Also it can communicate with some external softwares Chapter 1 Overview 3 Z El ta Y RR OOOO pect RPE BAER OO ONES A a a OREO ORE LOSS ZO ra ml E ty RS Ti le Si i E BK Kf ES i E KS K N 5 E KE y o eae OS ARO E K S E E i AAAA y i S n i Ky ty IS hs LTS Kf iy ae hy Ns ES SE e ist K
78. nu When using an external mesh file a typical problem is that too few boundaries are available Without any specific boundary informa tion the only way to define boundaries is to divide them into internal boundaries boundaries between bodies and outer boundaries based on body material information With only one body this would mean that there is only one outer boundary for the whole model 10 ELMER Front s User Guide 2 1 3 Model file Model file is an internal ELMER file containing all the model informa tion including the model geometry in ELMER Front specific format For ELMER Front the model file is the most essential file If the model file is deleted all model definitions are also lost At the very first stage an external geometry is read into ELMER Front When the user defines the model these definitions are stored in a model file Default name for this file is modelname emf The extension emf is an abbreviation for ELMER Model File When model file is saved all the model information which is rele vant for solving the problem is automatically stored also in a separate ELMER Solver control file Default name for this file is modelname sif The extension sif is an abbreviation for Solver Input File Both these file are stored in the model directory This directory can be set using the Model name and directories command in the Problem menu 2 1 4 Structural overview Figure 2 1 gives an overview of all files
79. odel Refer to the Model window section in the end of this chapter When boundaries are displayed in the Model window they are num bered using the same id numbers that are used in boundary tables Chapter 2 ELMER Front 15 All these windows have common rules and features for the data entry as explained below The first step in the data entry is to select the target body or boundary for the data After that definitions can be entered using the data entry fields in the window Some of the fields may however be disabled because they are not applicable for the target body or boundary For example if the user is entering a material definition for a body and the body does not have a flow equation defined it would not be possible to enter any flow related material data for the body In many windows data fields are devided into subsets by equation type These subsets can be activated and displayed using the equation type radio buttons in the area above the data fields Data in the currently active entry field can be reset to the previous value by pressing the Esc key on the keyboard If a field supports entering multiple values a space is used as a separator 2 3 3 Attaching parameter sets to bodies and boundaries When all necessary data for the new parameter set has been entered it is added to the list of parameter sets using the Add button under the parameter listbox If an existing parameter set is being modified the update is activ
80. oned above If a definition file is loaded this list is enlarged and modified and these changes are reflected in the data entry panels So loading a definition file can be seen as a mechanism to add new fields to the system When a model file is saved all new field names and their values are saved with the model file However it is important to notice that the field property definitions for the new fields are not stored in the model file If the model file is loaded later in a new ELMER Front session without first loading the original definition file s these new fields are considered unknown for the system and all the data related to them is removed from the internal data structures In this stage the original model file is still of course unmodifed but if the user now saves the modified model data all the data related to the new fields is permanently lost So it is essential to load proper definition files into the system before loading a model file which contains user defined fields It is the user s responsibility to keep record of the definition files related to any model file 98 ELMER Front s User Guide 5 3 Loading definition files A definition file is loaded automatically if a file named front edf is found in the ELMER _HOME lib directory or if the user has defined an environment variable named ELMER_FRONT_DEFINITIONS and it contains a file name refering to a definition file A definition file can be also
81. or the whole model for a body for a layer for an edge or for a vertex The density values given for an entity always overrides those given for the higher level entities The density can be given as an absolute value or a value relative to the global density value The actual density values in the middle of a layer are interpolated from the values on the border Three types of background meshes can be used for the interpolation e An explicit background mesh can be given as a set of points with associated density values Any mesh density values from the model are ignored e A delaunay triangulation can be made from the original geome try vertices e An orthogonal grid can be used to calculate the density values as a solution to a Laplacian boundary value problem The grid density can be chosen from three values 6 3 File structure The file consists of a hierarchy of records that contain keywords and data All keywords end with a colon The file is divided into words separated by any kind of whitespace characters so the file may be freely decorated by indentation or adding empty lines The file is case sensitive Most of the fields in the records are mandatory and must be given in a fixed order Several records may contain an optional mesh density field that has one of two keywords H or R The keyword H is followed by an absolute density value and the keyword R specifies a value relative to the global dens
82. rtegies for free triangular C None MeshH Relative meshes are moving front meth Mesh H m lo 0075 ods and the Voronoi vertex method Rs menti 1 0 Default value is the standard Mov ingFront method Other moving front options are SSSFMovingFront single seed single front and SSMFMovingFront single seed multi front methods These methods need a starting edge as seed The boundary id for this seed can be entered in the Meshing seed edge field e Background mesh Free triangular meshing starts from an auto matically created background mesh Delaunay is the default method Other options are regular background grids Grid SparseGrid and DenseGrid A dense background grid creates better quality meshes but it is also a slower method SparseGrid is faster but the mesh quality may be lower Options for these buttons are displayed in Figure 2 12 5 Mesh density value type radio buttons e None deactivates values on this level e Mesh H activates the Mesh H field to be used for entering an absolute mesh density value in this level e Relative activates the Relative mesh H field to be used for entering 66 ELMER Front s User Guide a scaling factor for mesh density in this level The actual mesh density value for this level is the product of the scaling factor and the model level density value Mesh structure When the Quad mesh element type is selected the fields at right are activated for input
83. ry is displayed in the Model window e Arrows on the left side are used for moving rotating and zooming the model e Rotate X Y Z checkboxes model rotation axis is locked to the selected axis e Draw bodies a CAD geometry 2D only is drawn in solid format For a mesh geometry this drawing mode displays the volume mesh by drawing the element edges e Draw surfaces mesh geometry is drawn using filled boundary ele ments only for 3D models e Draw edges CAD geometry is drawn using edges mesh geometry is drawn using boundary element edges e CAD geometry activates deactivates the display of the CAD ge ometry if CAD geometry is available e Mesh geometry activates deactivates the display of the mesh ge ometry if mesh is geometry available Chapter 2 ELMER Front 81 e Auto load mesh when selected a mesh is automatically loaded whenever a model file is loaded If the mesh is very large it may be useful to deactivate the autoload behaviour e Select bodies the bodies to be displayed are can be selected here e Display redisplays the Model window on the desktop if it has been closed or minimized e Reset resets the the graphics displyed in the Model window to its initial state 2 18 Model Window The Model window is opened automatically when a geometry input file is read into ELMER Front This window is used to display the model geometry and to offer a flexible interface for the model When model objects are select
84. s For details see the Window menu section in this chapter Modified data in entry fields is displayed using a red font until the modifications are accepted by pressing the Apply button In a window header an asterisk displayed after the window title in dicates that the data in the window has been modified Pressing the 14 ELMER Front s User Guide Apply button resets also this indicator 2 3 2 Windows with body and boundary tables A common factor to these windows is the Bodies listbox on the top left under the Bodies header On the right side of the window is a listbox which contains the parameter sets which are entered in the panel When these parameter sets are atteched directly to bodies like the equations or material properties only these two listboxes are visible In some windows data is attached to the boundaries and in these windows there is also a Boundaries listbox which displays all the boundaries for the currently selected body In the following list the Boundaries Boundary conditions and Mesh density window are boundary level windows other windows are body level windows e Edit menu Bodies Boundaries e Problem menu Equations e Model menu Initial conditions Body forces Materials Boundary conditions e Mesh menu Define Mesh Mesh structure Mesh density Note These windows are designed to be used in conjunction with the Model window because it helps to identify bodies and boundaries in the m
85. s more than one degrees of freedom 1 Field P 1 Hide 1 Initial Value 0 0 NOTE By default the dof identifier would be added to the base label which was earlier set to be Sound pressure This panel specific definition sets the label exactly to the user defined value 108 ELMER Front s User Guide Field P 2 Label Sound pressure B End Panel These flux and impedance fields are needed for the boundary conditions They cannot be concluded from the variable of the equation sound pressure so the user must add these fields to the system Panel Boundary Condition Field Wave Flux 1 This way it is easier to remember that the first component is the real part and the second component is the imaginary part Label Wave flux Re Field Wave Flux 2 Label Wave flux Im Field Wave Impedance 1 Label Wave impedance Re Field Wave Impedance 2 Label Wave impedance Im End Panel End Equation An existing equation is modified Equation Heat Equation NOTE Solver settings is a panel where new field can be added to the predefined equations because the related solving methods are built into the standard ELMER solver They have been Chapter 5 ELMER Definitions File format 109 left as a user defined fields because they are typically needed only for some specific problems Panel Solver Field Bubbles Type Logical Initial Value True This field will be hidden th
86. s the fields e Layerld A unique layer indentification a positive integer e An optional mesh density field e LayerType The layer mesh type Described below e A type dependent part Described below Chapter 6 ELMER Mesh Generator input file format 115 e Loops The number of loops e A list of loop records Loopld A positive integer Direction 1 or 1 If the direction is 1 the loop direction is inverted Edges The number of edges A list of signed edge ids negative means backwards The layer type can be one of the following e Connect Nodes are generated on the layer edges and connected with a delaunay triangulation e VoronoiVertex Nodes are inserted one by one into the place that has the greatest distance to the nearest existing node e MovingFront Nodes are inserted by taking an accepted mesh segment and inserting a third node so that a good triangle is produced The entire boundary is used as a starting front e SSMFMovingFront The same as MovingFront but the pro cess is started from a single seed position Advances to the di rection where the distance to the nearest node is greatest e SSSFMovingFront The same as SSMFMovingFront but ad vances more locally e QuadGrid A grid of quadrilateral elements The layer must have only 1 loop with exactly four edges The user must also make sure that the opposite edges will be subdivided into equal numbers of elements This can be done eas
87. st of boundaries This happens even though from the problem viewpoint the boundary segments could form a single physical boundary To simplify the problem it is advisable to simplify the CAD geometry to contain as few boundary segments as possible Chapter 2 ELMER Front 9 2 1 2 Mesh file A mesh file or a set of files is an external file where bodies are described by volume elements and the surfaces by boundary elements If no boundaries are given they are formed at body surfaces The mesh input file can be a 2D or 3D mesh file Supported input formats are e Abaqus mesh files inp e Fidap mesh files fdneut e I deas mesh files unv e ELMER mesh files mesh header Overview In ELMER external mesh files are saved in an ELMER specific format and the result files are named using the following scheme e mesh directory mesh header e mesh directory mesh nodes e mesh directory mesh elements e mesh directory mesh boundaries Here mesh directory refers to the directory where ELMER mesh files are stored This directory is created automatically and it is formed from the model directory and the mesh name using the following scheme mesh directory model directory MESHDIR mesh name Geometry definitions Contrary to a CAD geometry a mesh geometry can be edited Mesh boundaries can be split and combined by regrouping mesh elements that define the boundaries This procedure is explained later in the context of the Edit me
88. t 25 Inner and outer boundaries are sometimes called as boundary ele ments They should not be confused with mesh boundary elements Boundary names are by default in the form BoundaryN where N is a sequence number A boundary can be activated by selecting it from the boundary listbox or from the Model window The name of the selected boundary is displayed in the boundary name entry field where it can be edited Editing boundaries can be done only for one body or bodypair at a time Only one boundary can be split at a time Only complete boundaries can be combined Split and combine operations can be applied in any order and both operations can be cancelled using the undo command Multiple boundaries can be selected by pressing the Control key during a selection Note See also the Model Window section at the end of this chapter 2 8 3 Element Selection method A split operation for a boundary is done by selecting a group of mesh elements in the boundary and by forming a new boundary with this group The remain ing mesh boundary elements stay with Selection method the original boundary G By neiahbor Selecting the mesh elements can be done C Bu nomal by two methods y norma CO By plane 1 First method elements can be se lected from the graphics window Model C An window by painting them directly This is done by pressing the shift key and painting with the mouse cursor while pressing the left mouse button I
89. tbox it inherits certain prop erties from the active target body or boundary In the Model menu windows these properties are related to the equation type of the active body In the Mesh menu windows this property is the mesh structure of the body This property inheritance creates some restircitions on how parameters can be attached to target bodies or boundaries An attachment is not possible if the parameter and the target have con flicting properties For example it is not possible to attach a material property for a body which has only heat equation defined if this ma terial definition was originally created for a flow body To identify this matching an asterisk is used to mark parameter sets which match the selected body or boundary This asterisk is shown in the beginning of the parameter row When a body or an boundary is selected all those existing parameter sets which can be attach to the selected target are marked with an asterisk It is possible to select a parameter which is not marked with an as terisk This parameter can be edited and updated but it cannot be attached to the current target the Attach button is not active be cause it does not match this target When a parameter set is double clicked the first target to which this parameter is possibly attached is activated The next double click will activate the next target etc The buttons which are used to the handling of the paramter sets have the fo
90. tem is platform specific Favor GUl is the default and recommended value Giving more priority for running processes can make the user interface almost unresponsive Process table Ctrl T Process priority level 2 15 Window menu Commands in the Window menu can be used to control currently active ELMER Front windows e Close all closes all windows except the main window and the Model window e Close unmodified closes all windows where data has not been modified except the main window and the Model window e Window list displays a list of currently open windows This list can be opened as a separate window by clicking on the dotted line as shown in Figure 2 34 Clicking a window name in this list activates the window Window Close all Close unmodified ee a Window list Process table gt Process table Processor settings 7 Processor settings Solver settings i Solver settings Equations eset Equations Figure 2 34 Window list example 78 ELMER Front s User Guide 2 16 Help menu Index Contents Graphics info System info About Figure 2 35 Help menu 2 16 1 Graphics info Help Graphics environment info Pe E3 Line width range 0 5 10 0 Line width granularity fo 25 Figure 2 36 Graphics info window The Graphics info window displays some OpenGL related graphics hardware information T hese are non editable information fields Chapter 2 E
91. the mesh name as explained above e Current nof nodes the total number of nodes in the selected mesh e Current nof elements the total number of elements in the selected mesh e MeshH value m the default mesh element size for the whole model is defined with this value Values defined at lower level will overwrite this value Default value is derived from the average dimen sion of the model e Mesh scaling factor all mesh density values given derived or in herited in the model are finally multiplied with this factor Default value is 1 0 e Current this button sets the field value into the currently active value e Default this button sets the field value into the default value e Mesh structure this button opens a window for entering body level mesh definitions L2 e Mesh density this button opens a window for entering boundary level mesh definitions L3 e Generate mesh this button will generate the mesh using the cur rent mesh definition values Note that a new mesh is not added to the list of meshes until this button is pressed 64 ELMER Front s User Guide 2 12 5 Mesh structure Define mesh Mesh structure Body Level L2 Bodies Mesh structure sets 2 Water zi zi Attach Detach Add Update Delete Body rece ze Name Include body in mesh V Mesh name Mesh1 Values for mesh structure parameter Element type Nof elements 1st and 3rd edge Triangle C Quad
92. the step size in seconds in the interval e Steps in interval the number of steps in the interval e Output interval the output frequency in the interval Chapter 2 ELMER Front 41 A new timestep interval can be added by entering three values sepa rated with a space and then pressing the Add button In the example step size is 150 steps in interval 4 and output interval 15 because ev ery fifteenth timestep should be output this setting would not create any output from this interval New entries are added at the end of the table when the Add button or the En ter key is pressed The Insert button Timestep entry i ae inserts a new entry above the currently Step Steps in Output size s interval interval selected row in the table The currently active row may be updated by updat 2 0 10 1 ing the values in the Timestep field and then pressing the Update button The currently selected row may be deleted from the table by pressing the Delete button For each row in the list running cumulatives are displayed as the last three numbers Total cumulatives are shown in the Totals fields at the bottom of the window 2 10 5 Physical constants The Physical constants window is used to modify the default values for physical constants Modifying these values may be necesary when for example input values are in nonstandard units The constants are the gravity vector and the Stefan Boltzmann constant Physical constants Of
93. tion keywords in the order they must be in the input The letter N after the section name indicates that multiple section entries are allowed but each section entry must be identifed by a unique id number For example there can be multiple edge sections in the input but they must all be after the vertices and before the edge loops and bodies Header Vertices Edge N optional Edge Loop N optional Body N 86 ELMER Front s User Guide This order means that the geometry is defined hierarchically Lower lever elements must be given before the higer level elements which refer to them First all vertices are defined then the edges using theses vertices then edge loops and finally the bodies using these edge loops However it is possible to define a body using only edges or vertices For example if the geometry consists of one rectangular body the four corner vertices are enough to define the geometry On the other hand if the geometry consists of multiple bodies which have common boundaries it would be more effective to first define boundary edges which define the bodies because same edges could be used in multiple bodies Edge loops would be useful if some bodies are enclosed within other bodies because then same edge loops could be used in multiple bodies Data values can be either integers reals decimal numbers or strings Corresponding data type identifiers are Integer Real and String Normally it is not necesary to specif
94. tolerance or Steady Tolerance re o08 state tolerance for transient prob Residual output 1 lems this field sets the tolerance for stopping the iteration when multi Preconditioning ILUO ple equations are coupled to each rs None other For steady state problems it Diagonal sets the tolerance for stopping the de steady state iteration ILU2 ILU3 ILU4 ILUS 2 13 2 Processor settings This command opens a window for setting the number of processors reserved for the problem This parameter has meaning only in a par allel processing environment Solver settings Processor settings Al ES Settings for parallel processing Number of processors p E Cancel Apply Figure 2 31 Processor settings window 2 14 Run menu The Run menu commands are used to start other ELMER modules Before a module can be started all the necessary definitions and set tings should be completed If this not the case an error message box is displayed If the missing data is essential for the module the process cannot continue Chapter 2 ELMER Front 73 Generate mesh Ctrl F1 Calculate View factors AZ Calculate Gebhardt factors Ctl F3 Solver Ctrl F4 Postprocessor Ctrl F5 Select result file Ctrl O Process table Ctrl T Process priority level Figure 2 32 Run menu 2 14 1 Generate mesh Generate mesh command starts the ELMER mesh generator it cre ates a browsable log file 2 14 2 Calculate View
95. try is defined here Header Model Name Boiler model name is optional it can be defined later Dimension 2 dimension must be given Currently always 2 End each section ends with the keyword End Vertices Points a table of points starts Variable Index an argument variable is used to index the points Size 2 points as 2D coordinates Real type must be given for a table 1 0 000 0 000 note one argument value vertex id and a 2D point 2 0 000 0 010 3 0 063 0 010 4 0 070 0 030 5 0 070 0 110 Chapter 3 ELMER Geometry File format 91 6 0 070 0 120 7 0 075 0 120 8 0 075 0 030 9 0 065 0 000 10 0 000 0 110 End End Edge 1 Name Surface Vertices 5 10 End Edge 2 Name Water smtr Vertices 10 2 End Edge 3 Name Inner Vertices 23 4 5 End Edge 4 Name Kettle srf Vertices 56789 End Edge 5 Name Bottom Vertices 9 1 End Edge 6 Name Kettle smtr Vertices 1 2 End Body 1 Name Kettle Color 255 0 0 255 an End is needed to indicate the end of the table this is the section End edge number one water surface 5 and 10 are indices in the vertex table the water boundary at the symmetry line the inner boundary between the kettle and water this is a polyline edge the outer boundary of the kettle excluding the bottom an other polyline edge the bottom of the kettle the kettle boundary at the symmetry line body number one is the kettle color by RGB codes and a
96. tton This variable can be any of the variables solved in the model any of the model coordinates and for a transient problem it can also be time Figure 2 21 shows the variables available for a transient 2D problem with heat and flow equations Model Procedure definition for YELOCITY_1 Wariable none v none Coordinate 1 Coordinate 2 Pressure Temperature Time Velocity 1 Velocity 2 Figure 2 21 Argument variable list e Source file the source file for the procedure e Libraries possible external libraries needed by the compiler e Compiler the compiler command script e Edit source button opens the procedure source file for editing e Compile source button compiles the source file and append the procedure to the libary Table entry e Table checkbox clicking this checkbox opens a separete window for entering a data table This window is shown in Figure 2 11 4 and the fields are the following 56 ELMER Front s User Guide Model Clear a Clear panel Clear erty Edit FT Proc Iv Table Navier Stokes initial conditions Welocity R m s 10 Table entry for VELOCITY_1 of x Velocity Z m s 0 i Variable none Size1 1 Size2 1 Velocity P m s Pressure Pa 100000 Add Insert Update Delete 4 a T Line nbrs e Variable a possible argument variable for the table e Size 1 if the parameter is not a scalar this is the first dime
97. vel Note If the model contains a very large mesh and displaying the mesh is not necessary it may be useful to turn off temporarily the mesh au toloading This can be done by unchecking the first and third check boxes seen in the figure above and then selecting the Save for session command checkbox at bottom of this window and finally pressing the Ok button 3 Browser and Editor Browser command Editor command e Browser command field can be used to define an external program for file browsing e Editor command field can be used to define an external program for file editing 4 Data output methods Chapter 2 ELMER Front 31 These radio buttons are used to control where the output from other ELMER modules or the procedure compiler is directed or stored to Edit Settings Gebhardt factors browse Logwind Shellwind C None e Log file save output into a log file e Shell window direct output to the operating system shell window e None Nothing is displayed during the process Note Possible logfiles are stored in the Log directory This directory can be defined using the Model name and directories command in the Problem menu Logfiles can be viewed in the process browser window see the Process table command in the Run menu Logfiles are automatically deleted when an Elmer Front session ends 5 Save options V Save for session Save in model Save in file The following options are us
98. wise quotes are not necessary but it is safer to always quote the strings Quotes within quotes are not allowed All coordinate walues and other geometrical input parameters are by default in meters However it is possible to define an other input unit using the Unit keyword in the Header section For example if the user wants to enter input data in millimeters the input unit should be set to 0 001 All geometry related values coordinates circle radius etc in the input file would be multiplied with this factor In the model the geometry data is always stored as meters 3 2 1 The Header section Header Model Name s an optional string Model Directory s an optional string Dimension i currently only value 2 is accepted 88 Unit r End 3 2 2 The Vertices section Vertices Points Variable Index Size il i2 Real i1 r11 r12 i2 r21 r22 End End ELMER Front s User Guide input unit for all the geometry related data coordinates circle radius center etc default is 1 0 0 001 lt gt input data is in millimeters 1000 lt gt input data is in kilometers etc keyword for the point table must be given an optional keyword telling that the first value in each data row is and index id for the vertex table size If two integer values are given then i1 tells the number rows and i2 tells the number of coordinate values per row If only one integer value is given it tells the numb
99. y the type of the data because it can be concluded from the context It is not either necessary to specify the size of the data because data values are read till the next keyword and this way the size can be concluded from the data itself The size can be given using the Size keyword and one or two integers depending if data forms an array or a table If data forms a table like the vertex points in the Vertices section then the data type and size specifiers are always needed The size keyword must be before the type keyword Accordingly for example a list of edges could be given simply Edges 1234 or Edges Size 4 1234 or in the fully sepcified form Edges Size 4 Integer 1234 Chapter 3 ELMER Geometry File format 87 A string value could be given like Name First object or Name String First object The layout of the input data is free as long as numeric values are sepa rated with at least one space Of course using linefeeds and indenting makes data easier to check and read for users 3 On each line characters after or are interpreted as comments 3 2 The format In the following format description one of the letters i r s after a keyword means that some data value is needed in that place and the type of this data should be integer real or string A string value must be given in quotes if it contains spaces or if it is given without a preceiding String data type specifier Other
100. y will be entered they should be descriptive to make the identifying the bodies easier The name of the seleced body is displayed in the name entry field where it can be edited Chapter 2 ELMER Front 23 Bodies Al ES Water i kete ooo A zl l Cancel Apply Figure 2 6 Bodies window The color of the selected body color is shown on the Set color button This color is used when the body is displayed in the Model window If the Model window is not currently visible it can be opened by the Display model command in the Display menu or using the Display button in the main window Pressing the Set color button opens a color palette where the color for the body can be defined 24 ELMER Front s User Guide 2 8 2 Boundaries Boundaries 1 Kettle 4 Kettle srf Figure 2 7 Boundaries window Boundaries command opens a window where boundary names can are defined If geometry is read from an external mesh file ie model does not contain a CAD geometry boundaries can also be edited by splitting and combining them Boundaries edges or surfaces of separate bodies can be adjacent Such boundaries are called inner boundaries and the adjacent bodies are called body pairs Other boundaries are called outer boundaries When a body is selected all its outer boundaries are displayed in the boudaries listbox Inner boundaries can be displayed by selecting the corresponding body pair Chapter 2 ELMER Fron
101. y windows The Labels command in the Display menu can be used to switch theses labels on and off in the Model window 2 19 Control toolbar Most buttons in this toolbar have an equivalent command in menus e Save model save model file Chapter 2 ELMER Front 83 e Mesh opens the Define Mesh window e Load Unload mesh a two state button for loading and unload ing the mesh e Solve starts the solver e Results starts the postprocessor e Break interrupts current ELMER Front processing e Clear deletes all current messages in the message area e Process opens the process table e Info opens the model info window 2 20 Message area The window area in the middle of the main window is used to display information of various session events This is a cumulative list of warnings error messages and other session related incidents This list can be cleared using the Clear button in the main window 2 21 Status area Fields at the bottom of the main window display information on the current status of the model Red colored fields are meant to warn the user that the model may be incompletely defined concerning the parameters displayed in the status field However it is up to the user to decide if this really is the situation 84 ELMER Front s User Guide Equations 2 2 Flow Heat Timesteps fio Materials 2 2 Initial cond 22 Body forces fi ie Outer be 5 25 Inner be fi dal Meshes fi Figure 2 40 Status area
102. yed in the input panel area 2 for the adevetion diffusion equation and the checkboxes in this area control if these variables are active or not in the current equation set Each active variable activates also new entry fields in other panels Chapter 2 ELMER Front 47 where advection diffusion equation related data can be entered Be cause each variable is solved by a separate solver each active variable also creates its own entry in the Solver settings window This window can be reopened using the Variables button which is visible only in the advetion diffusion equation entry panel 2 10 9 Data checking As the user activates an equation certain data integrity checks are automatically done They are the following e Heat equation heat equation includes automatically heat conduc tion and constant convection can be added note constant convection values are given in the material parameters window The latent heat release can be selected only if some of the phase change models is activated e Navier Stokes equation when this equation is active it is possible to select computed convection for the heat and the advection diffusion equations 2 10 10 Equation solving order Equation solving order A ES Heat equation fi Navier Stokes 2 efault Cancel Apply D The Equation solving order is defined in this window The order can be changed by entering new order numbers These values can be any numbers only th

Download Pdf Manuals

Related Search

Related Contents

  トリオフィックス  SP1080 series Auto-Skim Skimmer  Zarafa Collaboration Platform  取扱説明書 [PDF形式]  Denver MTW-728TWIN  up to 300000V - Adler Instrumentos  DELL PowerEdge T310  

Copyright © All rights reserved. Failed to retrieve file