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AEROFLO User`s Manual

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1. Keyword Data Type Default Value Range Required SCHEME CHARACTER 3 BWI BW2 RK4 YES SUBON Integer 0 0 1 MAXITER Integer YES MAXSUB Integer 0 PRINTFR Integer 1 KTVDRK Integer 0 0 5 IBETA Integer 1 CFL Real 1 0 GLOBALDT Real YES SUBDT Real YES NDTAU Integer 99999 CFLMHD Real 1 0 DIAGONAL Integer 0 0 1 PRECON Integer 0 0 1 LREF Real 1 0 08 GLOBTOL Real 1 0E 30 SUBTOL Real 1 0E 03 ACCEL Integer 0 0 1 DAMPING Keyword Data Type Default Value Range Required TYPE Integer 0 0 5 ES2 Real 0 2 ES4 Real 0 01 FES2 Real 1 0 FES4 Real 2 0 MAXRED Integer 0 OMGAV Real 0 0 SRCONST Real 0 0 FILTER Integer Array 3 0 0 1 NFILTER Integer Array 3 0 ALPHAN Real Array 3 0 0 0 0 0 4999 ALPHAI Real Array 3 0 0 0 0 0 4999 ALPHA2 Real Array 3 0 0 0 0 0 4999 ALPHA3 Real Array 3 0 0 0 0 0 4999 ALPHA4 Real Array 3 0 0 0 0 0 4999 ALPHAS Real Array 3 0 0 0 0 0 4999 ORDERN Integer Array 3 10 0 10 ORDERI Integer Array 3 0 0 10 ORDER2 Integer Array 3 2 0 10 ORDER3 Integer Array 3 4 0 10 ORDER4 Integer Array 3 6 0 10 ORDERS Integer Array 3 8 0 10 148 SCASESPEC Keyword Data Type Default Value Range Required WALLTEMP Real 1 0 RMUM Real If MHD SIGMAREF Real If M
2. Mesh Format NULL IC File Name NULL N A 0 0 3 p ee Mesh Topology 81 Grid Size in I Direction Grid Size J Direction 1 Grid Size in K Direction 2 0 0000000E 00 O 0000000E 00 0 COMMENT BC SFACEBRC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND M c gt Comment mesh0 Block Name dE Position of Block Boundary 1 First I Face 10 Boundary Condition 10 Dirichlett Preferred Variable 2 u velocity 1 000000 Ee Preferred Value Il N 0 COMMENT BC SFACEBC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND ll Preferred Variable 3 v velocity 0 0000000E 00 0 COMMENT BC SFACERC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND m 7755 Preferred Variable 1 Density 1 000000 0 COMMENT BC SFACEEC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND E Preferred Variable 5 Pressure 3 375640 1 2 COMMENT BC OUTPUT Output Data
3. subgrid scale eddy viscosity Large scale flow results Figure 12 2 Procedures for LES simulation in AEROFLO 12 4 Direct Numerical Simulation DNS In the Direct Numerical Simulation DNS approach the Navier Stokes equations are solved without the introduction of any turbulence models All of the scales of motion are resolved from the smallest dissipative scale Kolmogorov scale up to the integral scale DNS provides very accurate simulation results and can be used to perform numerical experiments to obtain turbulence information that may be difficult or impossible to obtain in the laboratory To satisfy these resolution requirements the computational mesh must be able to resolve the Kolmogorov scales which are very tiny This makes DNS very expensive The computation cost of DNS sharply increases with the Reynolds number Today only very small Reynolds number flows can be simulated with DNS 12 5 Hybrid Models AEROFLO supports several hybrid RANS LES methods thus taking the advantages of both types of simulations the low simulation cost of RANS and high simulation accuracy of LES Detached Eddy Simulation Spalart Allmaras The Detached Eddy Simulation DES was developed to overcome the near wall problems occurring in LES calculations for the flow region close to the wall This can be done by using RANS and LES for different flow regions Regions near solid boundaries and regions where the turbulent length scale is l
4. BW2 10000 9 9999998 03 9 9999998 03 1 0000000 30 1 0000000E 03 3 0 2000000 9 9999998E 03 1 000000 2 000000 S 1 9 9999997E 05 0 0000000 00 0 0 4990000 0000000 00 4990000 4990000 4990000 4990000 NNNMN OO M M oM oM MM M GM oM r 0 0 4990000 0000000 00 4990000 4990000 4990000 4990000 10 0 zm mm GM GM M M oM 2 blocks 999 0 0 4990000 0000000 00 4990000 4990000 4990000 4990000 10 0 4 2 2 2 2 M M oM oS Figure 14 2 The Project File cdvductm afl for Flow Through Converging Diverging Duct two Block 101 OUTPUT PRINTFRQ 500 FORMAT TECPLOT SEND S DEBUG POINT 2 4 2 2 SEND SBLOCK BLOCKl Block 1 41x51 MESHFILE meshl plot3d FILETYPE PLOT3DEF ICFILE NULL PERIODIC 3 ISIZE 41 JSIZE 51 KSIZE 1 7 ORDER 2 ANGLE 0 0000000E 00 DISTANCE 0 0000000E 00 NOCROSS 0 SEND Two blocks SBLOCK are loaded NAME BLOCK2 MESHFILE mesh2 plot3d Block 2 41x51 FILETYPE PLOT3DF ICFILE NULL PERIODIC 0 0 ISIZE 41 JSIZE 51 KSIZE 1 ORDER 2 ANGLE 0 0000000E 00 DISTANCE 0 0000000E 00 NOCROSS Qi SEND H MM o9 COMMENT
5. DEBUG Diagnostic Point BLOCK Mesh Block Data FACEBC Boundary Condition First I Face 1 FACEBC Boundary Condition First I Face v 0 FACEBC Boundary Condition First I Face 1 Boundary Condition First I Face P 3 37564 Figure 6 1 The Project File cdvduct afl for Flow Through Converging Diverging Duct Cont 53 SFACEBC BLOCK SIDE TYPE VARIABLE DEPTH ISPLANE ISNORMAL SEND Position of Block Boundary 1 Last I Face Boundary Condition Type 23 Neumann COMMENT FACEEC BLOCK SIDE TYPE VARIABLE DEPTH ISPLANE ISNORMAL SEND COMMENT BLOCK SIDE TYPE VARIABLE DEPTH ISPLANE ISNORMAL SEND COMMENT SFACEBC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND COMMENT FACEEC BLOCK SIDE TYPE DEPTH ISPLANE ISNORMAL SEND Position of Block Boundary 2 First 2 Face Boundary Condition Type 1 Solid Wall COMMENT SFACEBC BLOCK SIDE TYPE DEPTH ISPLANE ISNORMAL SEND Position of Block Boundary 2 Last J Face SINITIAL VARIABLE VALUE SEND I Preferred Variable Preferred Value SINITIAL VARIABLE VALUE SEND 0 0000000E 00 SINITIAL VARIABLE VALUE FACEBC Boundary Condition Last I Face 0 Boundary Condition Last I Face 0 Boundary Condi
6. zr invalid grid valid grid Figure 8 4 Examples of Valid and Invalid 2D Grids 75 9 AEROFLO Output In this chapter detailed information about the AEROFLO output files is presented 9 1 Result Files The program generates output files that are controlled by the OUTPUT group keyword The output frequency and format are specified by PRINTFRQ and FORMAT Three output formats are supported CGNS TECPLOT and PLOT3D Both CGNS and PLOT3D formats were introduced in the last chapter The TECPLOT format is supported by TECPLOT a CFD post processing and results plotting software developed by Amtec Engineering Inc The TECPLOT format output files generated by AEROFLO can be directly read by TECPLOT without any modifications AEROFLO generates the following overall flow field results files ACGNS result output restart file myres cgns no matter which output format is selected An optional TECPLOT result output file myres dat if the output format is specified as TECPLOT Two optional PLOT3D result output files myres PLOT3D grid file and myres PLOT3Dq Q solution file if the output format is specified as PLOT3D result output restart file blockname tmp for each block with AEROFLO format In these files the output variables include x y Z P v and w values for general CFD problems additional for model and for K model values for turbulence flows additio
7. if the output format is TECPLOT The intermittent PLOT3D Q result files with names res1 3dq if the output format is PLOT3D For multi block calculations there are additional files that are outputted for the overset calculation for diagnostic purpose TECPLOT format mesh file resfe dat which highlights the overset nodes TECPLOT format mesh file resorphans dat which highlights the orphan nodes ATECPLOT format result file reselements dat which is in a cell based format This will be useful when the user does not want to see the result in the hole blanked region T A report file igreport dat which lists the status of overset nodes metr records the metrics for each block where represents the block number Start txt and end txt which are created when the computation starts and ends respectively There are also other binary files that contain the additional overset calculation information bink records the overset information for the hole blank regions dono records the overset information for donors records the overset information for receivers These files are useful for the restart calculation 9 2 Log Output At the beginning of the calculation the program will read the input files and these input parameters will be outputted on the screen for diagnostic purposes If there is an error detected in the project file input parameters the calculation is terminated and the corresp
8. to close the Add New BC dialog box To add the P 3 26325 boundary condition gt gt gt gt Click the Add Boundary Condition button to open the Add New BC dialog box In the Type drop down menu select Dirichlett In the Variable drop down menu select Pressure In the Value input box type 3 26325 46 10 Click OK to close the Add New BC dialog box c Lower Wall J 1 Face Select First J Face in the BC on Blocks drop down menu By clicking Refresh in the Graphic Controls dialog box the outlet boundary face is highlighted white colored in the Graphics Display dialog box To add the wall boundary condition Click the Add Boundary Condition button to open the Add New BC dialog box gt In the Type drop down menu select Solid wall Click OK to close the Add New BC dialog box d Upper Wall 7 51 Face Select Last J Face in the BC on Blocks drop down menu By clicking Refresh in the Graphic Controls dialog box the outlet boundary face is highlighted white colored in the Graphics Display dialog box To add the wall boundary condition Click the Add Boundary Condition button to open the Add New BC dialog box gt Inthe Type drop down menu select Solid wall Click OK to close the Add New BC dialog box Note If you set the above boundary conditions in a wrong way and you wish to modify it you can select the boundary
9. BLOCK MESHFILE keyword so that AEROFLO can find the grid files Other input files initial condition files and boundary condition files must be put in the project sub folder The AEROFLO executable command aeroflo exe or mpiaeroflo exe for parallel calculation should be in the directory of the project file You can do this by adding the AEROFLO installation directory to the PATH system environment variable or simply by copying the command aeroflo exe or mpiaeroflo exe into the directory of the project file The following steps are used to run a program in command line WINDOWS 1 From the Start menu select Run Programs gt A Documents E Settings Search D 7 Help and Support E Run Log Off Wenhai o Turn Off Computer ndows XP Home Edition 2 Type cmd then click OK to prompt the command environment 60 Type the name of a program folder document or Internet resource and Windows will open it For you Open cmd v 3 Change the directory to the folder where the project file resides For the sample problem created in Chapter 5 type cd c aeroflo test where c aeroflo test represents the directory of the project file cdvduct afl C WINDOWS System32 cmd exe Microsoft Windows Version 5 1 2666 lt C Copyright 1985 2661 Microsoft Corp C Documents and Settings Wenhaidecd c aerof lo test 4
10. COS VAL COS VARI INT VAL INT VARI SIN VAL SIN VARI In the future AEROFLO will be furnished with a function parser enabling the specification of more complicated equations of the boundary 138 16 10 INITIAL Keywords The sub keywords in the INITIAL keyword block specify an initial condition This input group may appear several times Each occurrence specifies a unique initial condition BLOCK Name of the block to which the boundary condition refers When the block is not specified the initial condition is applied to all blocks VARIABLE Variable to which the boundary condition refers Variable Density VALUE The value to which the initial condition will be set 139 16 11 OVERSET Keywords This keyword block is used to specify overset variables TYPE For calculations involving only non coincident node overlap or a combination of coincident and non coincident overlap use TYPE 0 which is the default In other words this keyword is not required for calculations involving only overset nodes or a combination of overset and coincident node overlap For calculations involving only coincident node overlap TYPE 1 is more appropriate This causes the program to pair the coincident node with exactly its donor node in the overlapping block No interpolation is required in computing the values from the donor nodes making the calculations faster If TYPE 0 is used for coincident node calcu
11. EveryNtimes D 5 Start Diagnostic Point in 2 2 2 Figure 4 17 Output Diagnostic Parameters Dialog Box The MHD Solver Parameters and Poisson Solver Parameters are the options for the MHD calculation which are not available in general CFD calculations 4 4 Graphics Display Dialog Box The Graphics Display dialog box serves two purposes 1 to present the computational grid graphically to help you visually while specifying boundary conditions and 2 to present log information in a text mode as the simulation progresses There are two modes graphics mode and text mode which correspond to those two purposes Figure 4 18 is a screen shot of the graphics mode In graphics mode the computational grid geometries are shown and the selected boundary is highlighted The graphics mode allows the user to visualize the selected surfaces and blocks which aids in the application of boundary conditions as well as block transformation 38 Graphics Display Figure 4 18 Graphics Display Dialog Box in Graphics Mode Figure 4 19 is a screen shot of the text mode In text mode the log information of the simulation will be outputted The performance of the Graphics Display dialog box is controlled by the Graphics Control dialog box which will be introduced in next section 29 Graphics Display Global variables successfully read Overset variables successfully read Turbulence variables successfully rea
12. H 15 hip 4 04 h 8 65h Figure 5 1 Physical Domain for Converging Diverging Duct Calculation The boundary conditions for the problem are summarized in Table 5 1 below Boundary Conditions Inlet u 1 v 0 1 P 3 37564 Outlet Ox 0 0v 0x 0 Op Ox 0 P 3 26325 Lower Wall solid wall Upper Wall solid wall Initial Conditions 1 v 0 1 3 37564 Table 5 1 Boundary and initial conditions for flow through a converging diverging duct The procedures for solving this problem are in accordance with the general procedures discussed in 42 Chapter 3 Each of these steps is described in the following sections 5 2 Getting the Computational Grid The computational grid file mesh 001 PLOT3D is available in the directory samples cdvduct under AEROFLO s installation folder It is a single block grid with PLOT3D format The grid size is 81x51x1 The geometry of the grid is shown in Figure 5 2 Y Lod L Figure 5 2 Computational Grid for Converging Diverging Duct 5 3 Setting Up the Project File Using the AEROFLO GUI The project file is also available for this problem cdvduct afl in sample directory However it is highly suggested that you follow the steps described in this section to prepare your own version of the project file This will familiarize you with the AEROFLO GUI and teach you how to solve a CFD problem in AEROFLO To create the project file you nee
13. file do not take effect However you may also delete them if you want the project file to be cleaner 69 8 Prepare AEROFLO Mesh File In this chapter we will introduce the requirement for the AEROFLO mesh file and the details of each kind of file format 8 1 General Requirements The grid must be provided by the user and only structured grids are supported by AEROFLO The user can generate grids by using grid generation software AEROFLO does not generate grids High quality grids will make your calculation faster and more accurate while low quality grids may cause the calculation to diverge or even cause unexpected errors in AEROFLO High quality grids always require that grid not be too loose for the problem grid be fine enough in the region where the flow quantities have a high gradient The grid spacing vary smoothly grid stretching not be too severe AEROFLO solves CFD problems in a block by block fashion In other words a CFD problem will consist of several structured blocks containing grid points The grids must be generated separately from AEROFLO Each block that makes up part of a CFD problem must be described in the AEROFLO input file The keyword for describing a block is the BLOCK command The BLOCK command may be used several times in an input file as many times as blocks that make up the project Each block description includes a name for the block a grid file and path to the grid
14. read PLANE points 6 DDHDDDDDDDDDDDDDE 90909 DDDDDDDDDDDDDDE pp You may also use the input output redirecting operator lt and gt operators to assign the project file to aeroflo exe directly and to output the log information to an output file For example by typing aeroflo exe lt cdvduct afl in Step 3 AEROFLO will run directly and the file name inputting step step 4 will be omitted Moreover if you do not want to print the log information on the screen and want to save it in a text file say output txt you only need to type the execution command by aeroflo exe lt cdvduct afl gt output txt in Step 3 UNIX 1 Open a UNIX shell 2 Change the directory to the project folder 3 Run the code by typing np n mpiaeroflo lt project file name 7 2 Restarting from a Previous Calculation In Chapter 5 we introduced how to pause and resume an AEROFLO calculation in the GUI The restart calculation can also be carried out in command line mode The restart calculation is possible because the AEROFLO output files contain the complete flow field information at the moment of outputting Therefore these files can be used to restart a terminated calculation There are two kinds of files that can be used to restart the previous calculation the CGNS output file myres cgns or the AEROFLO output files BLOCKNAME tmp To restart a calculation from these files you simply
15. stress or flux terms These SGS terms represent the influence of the small scales on the larger scales After the SGS terms have been introduced the filtered equations can be solved to obtain the large scale components of the flow The Smagorinsky Model The Smagorinsky model is the simplest sub grid scale model The SGS stresses are calculated using an eddy viscosity model The approach for calculating the eddy viscosity in LES is analogous to the mixing length theory However a coefficient used in the eddy viscosity model Smagorinsky coefficient is not universal to every problem In AEROFLO C is set to be 0 092 which is suitable for a wide range of flows The Dynamic Smagorinsky Model In the Dynamic model the Smagorinsky coefficient is locally and dynamically calculated based on the information on the resolved scales A grid filter and test filter which have varying widths are used and the Smagorinsky coefficient is calculated based on the scale invariance assumption that C is the same at the grid and test filter levels Germano s identity 9 The procedures for LES simulation in AEROFLO are shown in Figure 12 2 LES model Navier Stokes Equations Filtering with Calculate subgrid scale eddy filter function viscosity using Smagorinsky i model Filtered Navier Stokes Equations i Unclosed terms SGS terms SER Calculate SGS terms from
16. 1 VALUE 1 0 END INITIAL VARIABLE 2 VALUE 0 9961947 END INITIAL VARIABLE 3 VALUE 0 0871557 END This is equivalent to the following initial conditions p 1 0 u 0 9961947 v 0 0871557 w 0 1 P S yM As shown above the values of w and P remain the same as the default AEROFLO initial values 10 3 Initial Conditions Input File An initial condition file may be supplied with each block and specified with the block description The command to specify an initial condition file with a block description is BLOCK ICFILE ICFILE will contain a character value specifying the path to an initial conditions data file for the block The initial condition file must contain values for all grid points of the block specified by the block size The initial condition file must be an unformatted binary file with data layout as shown below General CFD IL JL KL ITERATION TIME U V W P RHO 80 Turbulence Flow Spalart Allmaras IL JL KL ITERATION TIME U V W P RHO SP IL JL KL ITERATION TIME U V W P RHO BFIELD IL JL KL integers representing the grid size in i j and ITERATION current iteration step 0 for a new problem TIME current time 0 0 for a new problem U V W P RHO three dimensional arrays exactly of size IL JL KL for the u velocity v velocity w velocity pressure and density variables SP three dimensional arrays exactly of size IL JL KL for the Spalart Allmara
17. 1 2 MIN fr Ay Az be used 124 Ay Az represent mesh spacing at cells in the mesh PRECON Determines if preconditioners will be used for the time integration Preconditioners are recommended for very low Mach number calculations lt 0 1 Otherwise the required GLOBALDT or time step size required for the calculation will be small making the calculations expensive IBETA Controls whether the scheme computes the sub iteration time step size or if the CFL is used to automatically compute the sub iteration time step and drive sub iterations to convergence Takes on values of 0 or 1 If the value is 0 the value of SUBDT is used as the sub iteration step size Otherwise a sub iteration step size is computed using the CFL number provided CFL The CFL number is used in conjunction with IBETA 1 to compute the sub iteration step size CFLMHD CFLMHD number is used in conjunction with IBETA 1 to compute the sub iteration step size for an MHD calculation NDTAU NDTAU is the number of steps between the updating of the sub iteration step size Used in conjunction with IBETA 1 KTVDRK Determines the version of Runge Kutta employed This input is only relevant if is the time integration scheme 3 uses the third order Runge TVDRunge3 4 uses the fourth order Runge TVDRunge4 Otherwise the standard formulation is used LREF 125 Used in conjunction with the preconditioner PRECON 1
18. AIAA Paper 2000 2330 Fluids 2000 Denver CO Ladeinde F 1998 Truly Automatic CFD Mesh Generation with Support for Reverse Engineering AIAA Paper 99 0828 156 Reference 10 11 12 13 14 15 16 17 Abid R Evaluation of Two Equation Turbulence Models for Predicting Transitional Flows Int J Engng Sci Vol 32 6 1993 pp 831 840 Anderson D A Tannehill J C and Pletcher R H Computational Fluid Mechanics and Heat Transfer McGraw Hill New York 1984 Beam R M and Warming R F An Implicit Factored Scheme for the Compressible Navier Stokes Equations Journal Vol 16 No 4 1978 pp 393 402 Germano M Piomelli U Moin P and Cabot W H A Dynamic Subgrid Scale Model for Compressible Turbulence and Scalar Transport Phys Fluids A 3 7 1991 pp 1760 Launder B and Sharma B Application of the Energy Dissipation Model of Turbulence to the Calculation of Flow near a Spinning Disc Lett Heat and Mass Transfer 1 1974 131 138 Lele S K Compact Finite Difference with Spectral Like Resolution Journal of Computational Physics Vol 103 No 1 1992 pp 16 42 Menter F R Zonal Two Equation k omega Turbulence Models for Aerodynamic Flows AIAA 1993 2906 Pulliam and Chaussee D S Diagonal Form of an Implicit Approximate Factorization Algorithm J Comp Phys 39 2 1981 pp 347 Pope S B Turbulence Flows Cambridge
19. BC 1 SFACERC BLOCK BLOCK1 SIDE 1 10 VARIABLE VALUE 1 000000 e DEPTH 2 5 ISPLANE y ISNORMAL 1 SEND COMMENT BC 2 FACEBC BLOCK BLOCK1 SIDE l5 TYPE 10 VARIABLE 3 VALUE 0 0000000 00 DEPTH 2 5 ISPLANE 0 ISNORMAL 1 5 SEND COMMENT BC 3 FACEBC BLOCK BLOCK1 SIDE 1 TYPE 10 VARIABLE d VALUE 1 000000 DEPTH 2 4 ISPLANE y FA D Figure 14 2 The Project File cdvductm afl for Flow Through Converging Diverging Duct two Block Cont 102 ISNORMAL SEND COMMENT FACEBC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND BC 4 BLOCKl 3 375640 COMMENT SFACEEC BLOCK SIDE TYPE DEPTH ISPLANE ISNORMAL BC OSIDE SEND OBLOCK BLOCK2 Type 2 Coupling boundary condition Specifies the block to which the current block is coupled COMMENT SFACERC BLOCK SIDE TYPE DEPTH ISPLANE ISNORMAL SEND COMMENT FACEBC BLOCK SIDE TYPE DEPTH ISPLANE ISNORMAL SEND BC BC BLOCKl BLOCKl COMMENT SFACEBC BLOCK SIDE TYPE DEPTH ISPLANE ISNORMAL BC OSIDE SEND OBLOCK BLOCK2 BLOCKl COMMENT FACEBC BLOCK SIDE TYPE VARIABLE DEPTH ISPLANE ISNORMAL SEND COMMENT FACEBC BLOCK SIDE TYPE BC BC VARIABLE D
20. BLOCK Keywords The sub keywords in the BLOCK keyword block specify a mesh block They provide data such as the dimension of the mesh location of the grid file and initial condition file as well as a unique name for the block This input group may appear several times Each occurrence specifies a unique mesh block All projects require at least one block be specified NAME A unique name for identifying the block MESHFILE Path or location of a grid file for the block FILETYPE Format of the grid file is as follows CGNS CGNS file format specifies the grid and possibly the initial conditions AEROFLO AEROFLO file format specifies the grid as well as the initial conditions PLOT3D PLOT3D file format specifies the grid ICFILE An initial condition file to be used if the initial condition is not contained in the mesh file If no initial condition file is specified and the initial conditions are not read from the grid file an initial condition of 0 0 will be assumed for the velocity field 1 yMa for the pressure and 1 0 for the density See Chapter 10 for initial conditions specification ISIZE JSIZE KSIZE Size of the grid For instance ISIZE 245 JSIZE 50 KSIZE 3 which describes a 245 x 50 x 3 grid PERIODIC Periodic description of the block This keyword expects three integer variables representing the periodicity 132 description in the 7 j and k directions The keyword expects three val
21. Blocks Add New Block Selected Block BC on Blocks Add Boundary Condition Selected BC Dirichlett on Pressure Modify Selected BC Delete Selected BC Display Controls Show Hide block Figure 4 7 Manage Blocks Dialog Box Figure 4 8 is a screen shot of the Add Modify Block dialog box This dialog box opens when you click the Add New Block or Modify Selected Block buttons You can define or modify the block name in the Block Name input box The Mesh Format drop down menu allows the format of the mesh to be selected AEROFLO supports the following formats PLOT3D CGNS and AEROFLO formats The No of nodes to place at overlaps drop down menu controls how many fringe nodes are used at block boundaries for a multi block calculation The Topology drop down menu options allow you to indicate the topology of your grid block in each of the grid directions Options include Plane O grid periodic and 2D grids The Load Block button opens up a file navigation dialog box to enable you to load a grid block file The Mesh File text box shows the name of the mesh file that is currently loaded The Transform 28 Block button opens up the Transformation dialog box which enables you to specify an initial transformation of the block Transformation operations include scaling translation and rotation AEROFLO allows the project to import the initial conditions from an initial condition file for each of the block The Add Initial Conditions F
22. Converging Diverging Duct Cont Spalart Allmaras Ma 0 08 0 16 0 24 0 33 0 41 0 49 0 57 0 65 0 73 0 82 0 90 0 98 1 06 1 14 1 22 Abid Ma 0 08 0 16 0 24 0 33 0 41 0 49 0 57 0 65 0 73 0 82 0 90 0 98 1 06 1 14 1 22 Figure 7 2 The Mach Number Contour for the Modified Converging Diverging Duct Flow Compared with Original Results 68 Discussion Note To restart a calculation the user sets the previous calculation results to be the initial condition of a new calculation These previously calculated results can be found in myres cgns in the CGNS format or in meshname tmp in the AEROFLO format These files can be loaded as mesh files for each of the blocks Simply change the mesh file name and type in the project file For multi block problems AEROFLO outputs only one myres cgns file which contains the information for all of the blocks To restart from this file simply let all of the blocks load the mesh files from this file For multi block problems AEROFLO outputs the meshname tmp files for every block To restart from these files let every block load its own tmp file If you look at the revised project file you will find that the last part of the file is still set with the global initial conditions In AEROFLO if the initial condition data is loaded it will automatically overwrite the global initial conditions Therefore the global initial condition settings in this project
23. Figure 15 1 Simple 2D Example of Automatic Coincident Node Overlapping of Two Blocks a Original blocks supplied by user b Blocks showing the ghost nodes following the automatic coupling Assuming both blocks have the same ijk orientation as indicated in Figure 15 1 the command for coupling both blocks would be as follows FACEBC BLOCK BLOCK1 SIDE 5 TYPE 2 OBLOCK BLOCK2 OSIDE 6 END FACEBC BLOCK BLOCK2 SIDE 6 TYPE 2 OBLOCK BLOCK1 OSIDE 5 END The result of the above command is shown in Figure 15 1 b Note that the coupling process is transparent to the user as coupled or ghost nodes are not included in output files To view the details of the coupling or grid assembly plot the resfe dat file which is generated each time a grid assembly is done in the 108 pre processing stages of a calculation 15 1 2 Partial Coupling Grid Blocks The example provided in this section considers the partial coupling of grid blocks a b Figure 15 2 Simple 2D Example of Automatic Partial Coincident Node Overlapping of Two Blocks a Original blocks supplied by user b Blocks showing the ghost nodes following the automatic coupling Assuming both blocks have the same ijk orientation and number of grids are as indicated in Figure 15 2 the command for coupling
24. Here we do this by directly editing the project file To do this use the following steps 1 Open the project file by using any text editor software 2 Under the TURB group keyword change the value of the TURBTYPE keyword to 5 represents Spalart Allmaras model and delete the TUVALUE and RESET keywords these keywords are only meaningful for type turbulence model 3 Under the SPATI AL group keyword change the values of the SCHEME keyword to 33 33 999 33 represents the WENO scheme Also change the value of the METRI C keyword to 13 13 represents the WENO metric differencing scheme Delete the CUTOFFI 63 ISOTROPI ICUT CUTOFF ISOTROPJ and JCUT keywords as they are only meaningful for Roe schemes 4 Under the TI MESTEP group keyword change the value of the MAXI TER keyword to 5000 and the value of the GLOBALDT keyword to 0 005 Under the OUTPUT group keyword change the value of the PRINTFQ to 200 6 There are two ways to complete this step Choose one of them a Under the BLOCK group keyword change the value of the MESHFILE keyword to myres cgns and the value of the FILETYPE keyword CGNS b Under the BLOCK group keyword change the value of the MESHFILE keyword to meshO tmp and change the value of the FILETYPE keyword to AEROFLO 7 Save the file and check to make sure that either myres cgns or meshO tmp is in the subfolder Using the steps in Section 7 1 to run the project file in
25. LREF is a reference length scale SUBTOL When sub iteration is used ISUBON 1 sub iteration is performed up to the maximum number of sub iterations specified by MAXSUB or until sub iteration convergence The convergence tolerance is specified by SUBTOL and represents the ratio of the residual at first sub iteration to the residual at convergence GLOBTOL For a steady state simulation GLOBTOL represents the convergence tolerance This tolerance represents the ratio of the residual at first iteration to the residual at convergence Once convergence is reached the iterations terminate even if MAXITER has not been reached For an unsteady state simulation set GLOBTOL to a very low value or leave it at its default value to ensure that the calculations do not terminate prematurely ACCEL Set this variable to 1 to use the convergence accelerating scheme This scheme increases the value of GLOBALDT as the solution error reduces 126 16 5 DAMPING Keywords The sub keywords in the DAMPING keyword block specify the damping or filtering data When not provided no damping or filtering is applied TYPE This variable determines the type of damping or filtering scheme that will be employed Not used Damping Filtering every sub iteration Bh WN HL Filtering every iteration or after all sub iterations are completed ES4 ES2 FES4 FES2 OMGAV SRCONST These are implicit damping control parameters FILTER This va
26. Step Size input box is used to specify the sub iteration step size The Sub Iteration Tolerance input box is used to specify the value of the residual at which the calculations are considered to have converged for the current time step The CFL No input box is used to specify the CFL number to use with the variable time step option for calculating the time step 32 Time Integration Scheme Time Scheme Full Formulation i Use fixed time steps Gj Use preconditioner Time Steps Max No of Steps Time Step Size 0 010 Tolerance lo 10E 29 Sub Iterations Max No of Iterations Iteration Step Size 0 010 Tolerance lo 10 02 CFL No Figure 4 12 Time Integration Scheme Dialog Box Spatial Differencing Scheme button This button opens a Spatial Differencing Scheme dialog box which is used to specify the spatial differencing scheme Figure 4 13 is a screen shot of this dialog box The Scheme Specification dialog box provides the environment for specifying the spatial differencing scheme AEROFLO allows the specification of various spatial differencing schemes in different blocks and in different directions The spatial scheme options include Compact scheme Roe schemes e MUSCL scheme e WENO schemes Once a spatial scheme has been selected parameters can be added via the subsequent dialog boxes that are activated The New Specification button creates a new spatial scheme specification for the CFD proj
27. The type of simulation 2 general CFD MACH Mach number for simulation REYNOLDS Reynolds number for simulation PR Prandtl number for simulation TURB Turbulence modeling data TURBTYPE Turbulence model 7 Abid TUVALUE Turbulence intensity for model RESET Set the initial k values 1 yes 0 no SPATIAL Spatial differencing scheme data SCHEME Spatial differencing scheme for all directions 5 MUSCL 999 2D problem METRIC Metric differencing scheme 0 2 order central differencing VISCOUS Viscous specification in all three directions 0 inviscid 1 viscous Time differencing scheme data SCHEME Time differencing scheme BW2 Beam Warming MAXITER Maximum number of iterations GLOBALDT The time step size for iteration DAMPING Damping or filtering data OUTPUT Output controlling data PRINTFQ Frequency of printing results FORMAT Specifies the preferred output format TECPLOT TECPLOT format BLOCK DEBUG Debugging and monitoring data Mesh block data NAME Name for the mesh block MESHFILE Location of the grid file for the block FILETYPE Format of the grid file PLOT3D PLOT3D format ICFILE Location of the initial condition file for the block NULL no file PERIODIC Periodic description of the block in all directions 0 no periodicity 3 2D problem ISIZE Size of t
28. To return it to a grayed dialog box you can simply click the Edit button on the right of the button that you wish you access It is highly suggested that you save the project file after every step listed in this tutorial To save the file click the Load Save Project button and then click Save Project 44 7 Load the Grid File 8 9 a the grid file samples cdvduct mesh 001 PLOT3D AEROFLO installation folder to your project subfolder c aeroflo test cdvduct b When you return to the main graphic interface click Manage Grid Blocks button This opens up the Manage Blocks dialog box c Click the Add New Block button to open Add New Block dialog box d Inthe Block Name input box type the name for the on going grid block Here we use mesh e Inthe Mesh Format drop down menu select PLOT3D since the grid file is in PLOT3D format f Click the Load Block button to open a file navigation dialog box Change the directory to the project subfolder c aeroflo test cdvduct to select the grid file Click Open to load the grid file g Ifthe loading is successful a message will pop up to show the mesh size Click OK to close the Add New Block dialog box and finish the mesh loading View the Grid Click the Graphics On button in the Graphics Control dialog box to change the Graphics Display dialog box to the graphic mode The geometries of
29. Two Block Simulation of Converging Diverging Duct Flow Compared to the Single Block Results 105 14 3 Automatic Domain Decomposition AEROFLO can decompose your domain to match the available number of processors independent of the original number of blocks For example you could ask the code to solve a 4 block problem on 10 processes or conversely 10 blocks on 4 processes In these cases the code will internally perform decomposition coarsening of the original block structure Note that input and output are in terms of the original block structure To use this capability you only need to specify the number of processes in the syntax for submitting the job for execution For the example in Section 14 1 the 2 block converging diverging duct flow problem the command to execute AEROFLO on 2 processes will be mpirun np 2 mpiaeroflo lt cdvductm afl However to run the 2 blocks on 4 processes you will use mpirun 4 mpiaeroflo lt cdvductm afl Note that the minimum number of grid points in any direction that required for splitting is 20 Below this AEROFLO does not allow you to split the original blocks 14 4 Automatic Determination of Interior Block Interface AEROFLO also supports a tool that can automatically determines the connection information between the blocks You do not need to input the interior boundary conditions for multi block problems AEROFLO can automatically detect which blocks are adjacent and implement the
30. allowed to interpolate and provide values for it 140 NUMITER is applied progressively such that the closest cells are always chosen The default value of NUMITER is 2 USEADT This sub keyword is used to indicate whether octree search coded procedures should be used for the overset donor search process This results in a faster search process The value of this sub keyword is 0 or 1 The default value is 1 which indicates that octree procedures should be used 141 16 12 MESHCUT Keywords This keyword block is used to define a region of one or more blocks that will be blanked by another block CUTTER Primary cutting block Sections of this block will cut the other blocks specified in the BLOCKS list BLOCKS List of blocks that will be cut when they overlap the block specified by the keyword CUTTER ORDER Offset of nod at the edge of the cut PERIODIC This sub keyword specifies how the cut will be completed The values of PERIODIC are 0 The cut extends all the way to the boundary of the cutting block with an offset for interpolation 1 2 3 The cut extends to the boundaries of the cutting grid without any offset 4 cut extends to j or 1 without any offset or overlap The cut extends to j or End without any offset or overlap 142 16 13 POINT Keywords This keyword block is used to define a geometric point in the project COORDS Coordinates of the point as real numbers separat
31. around at specified face 61 j axes 62 k axes 7 Slip wall 80 Equation 90 User Defined VARIABLE Variable to which the boundary condition refers Density velocity Pressure The variable input is only required for the Dirichlett TYPE 10 no stress TYPE 23 and flux TYPE 24 boundary condition types 135 VALUE This represents the value to which the boundary conditions will be set The value input is only required for the Dirichlett TYPE 10 flux TYPE 24 and freestream TYPE 32 boundary condition types DEPTH Number of nodes at the boundary to which to apply the boundary condition Defaults to BLOCK ORDER or GLOBAL ORDER For instance for a multi block overset formulation to maintain fourth order accuracy at an overset boundary for a centered formulation at least two nodes at the boundary must be specified as overset nodes ISPLANE This variable determines if the surface normal direction will be computed at every node on the boundary If ISPLANE 1 the normal is calculated only once as it is assumed that all of the nodes lie on a plane This results in a faster scheme Because boundary conditions are applied at every sub iteration it is important to designate plane surfaces to speed up the calculations This variable takes on a value of 0 or 1 The default value is ISPLANE 1 ISNORMAL This variable determines if boundary nodes are assumed to be normal at the boundary If I
32. command line 8 The program will read the restart files the modified project file and the restart block data myres cgns or meshO tmp to restart the calculation Figure 7 1 shows the modified project file You can compare it with Figure 6 1 to see where the file is modified The simulation result is shown in Figure 7 2 64 cdvduct afl SGLOBAL TITLE Converging Diverging Duct FOLDER cdvduct SIMTYPE 2 MACH 0 4600000 REYNOLDS 732677 0 PR 0 7200000 ORDER 2 BCSTYLE 2 SEND SOVERSET SEND STURB Change TURBTYPE 5 Change TURBTYPE to 5 Spalart Allmaras Turbulence SEND and delete TUVALUE and RESET Mode SSPATIAL SEND SCHEME 33 1 320 2999 Change SCHEME to 33 WENO for METRIC 13 i I J directions and METRIC to 13 Change VISCOUS i VISCHEME WENO Delete CUTOFFI Spatial VISCMON 1 ISOTROPI ICUT CUTTOFFJ Scheme SUTHERLN 0 3800000 ISOTROPJ and JCUT Il lt STIMESTEP SEND SCHEME BW2 MAXITER 5000 GLOBALDT 0 005 Change MAXITER to 5000 and Change SUBDT 9 9999998 03 GLOBALDT to 0 005 Time Steps GLOBTOL 1 0000000E 30 SUBTOL 1 0000000E 03 SDAMPING TYPE 3 ES2 0 2000000 54 9 9999998 03 FES2 1 000000 FES4 2 000000 MAXRED 1 OMGAV 9 9999998E 03 SRCONST 0 0000000E 00 FILTER 0 0 0 NFILTER i 5 1 ALPHAN 30
33. computational costs However the approximate factorization and diagonalization procedures introduce errors at each time step which can degrade the temporal accuracy of the simulations The sub iteration method is used to remove these linearization and approximation errors In general the larger the time step and the grid sizes the more the number of sub iterations required at each time step in order to converge the sub iteration operation Note that to obtain an accurate oscillation free upwind type numerical scheme implicit or explicit artificial damping dissipation terms can be added to the central or forward difference schemes which will suppress the oscillations This is the damping or filtering method In AEROFLO the damping scheme developed by Pulliam is used for the Beam Warming scheme The damping parameters are set with the SDAMPING keyword The parameters for the time integration scheme are set by the STIMESTEP keyword Good time step sizes should be given by the user If the time step size is too large the calculation may be not able to converge and the solver may be terminated A small time step size leads to an expensive computational cost The selection of the time step size depends on both the flow conditions and the numerical schemes A trial and error process is usually required in order to determine a good time step size 13 4 Selecting Numerical Schemes The selection of an appropriate numerical scheme depends on the
34. coupling between them You only need to provide the conditions on the physical boundaries of the problem To use this tool you need to insert the keyword Global SURMATCH 1 in the setup file 106 15 Performing Overset Calculations AEROFLO can complete multi block calculations that involve coincident node overlap or non coincident node chimera or overset overlap between blocks AEROFLO multi block calculations are also parallel calculations and the number of nodes used must be equal to the number of blocks However the blocks may be of different sizes To perform multi block calculations the user simply has to indicate the overset boundaries like other boundary conditions with the FACEBC keyword The boundary condition type for the overset boundary is type 3 All other boundary condition variables that define the boundary are indicated as usual For instance on an I 1 face first 1 face if only part of the face is overset within another block then the j and k node limits may be indicated with the JBCS JBCE and KBCS KBCE keywords of the SFACEBC command AEROFLO also includes additional commands that help to speed up the calculations at an overset boundary These commands are invoked using sub keywords of the OVERSET keyword and are explained below 15 1 Basic Multi Block Calculations with Coincident Node Overlap AEROFLO can easily perform calculations involving basic multi blocks with the blocks connected such that t
35. damping functions to account for the viscous effects in the region close to the wall With different damping functions and values of the model coefficients there are many low Reynolds number models Developed by Launder and Sharma in 1974 the Launder Sharma k e model is able to obtain good results for internal flows Abid s k e model Developed by Abid in 1993 Abid s k e model is another low Reynolds number model In this model a wall distance unit is used to construct the damping functions in order to obtain a reasonable near wall distribution of the damping functions Menter s SST model For boundary layer flows the k o model has advantages both in the treatment of the viscosity in the near wall region and in its ability to account for the effects of pressure gradient However this model has difficulties in the treatment of the non turbulent free stream boundaries which the k e model appears to handle quite well In 1994 Menter developed a shear stress transport SST k model to combine the k e and k o models taking advantage and avoiding the shortcomings of both models This is done by introducing a blending function which is zero close to the wall a k c model and unity far away from the wall k e model High Reynolds number k e model As opposed to the low Reynolds number models the high Reynolds number models do not focus on the viscous wall region Instead wall functions are introduced to avoid expensive near
36. file a file type specification an initial conditions file size of the grid and periodic specification for the grid 8 2 Grid Format AEROFLO supports three kinds of grid formats CGNS PLOT3D and a native AEROFLO format Note that these formats support both grid files and solution files In solution files both the grid information and the solution variable quantities are written in a whole file Therefore these formats are also used for the output files and initial condition files in AEROFLO Detailed information about each grid format is given below CGNS File Format The CGNS format was developed by the CFD General Notation Systems group an organization of CFD 70 software developers The format consists of a description for recording grid and solution data as well as boundary conditions data As a result a CGNS input file may contain both grid and initial conditions for a block The CGNS format is supported by most grid generation software The layout of AEROFLO data in a CGNS file is shown in Figure 8 1 Version AEROFLO Info base data Base Zone 1 Zone 2 Zone n 1 zone Iteration Block name Block name Block name processor Iteration Time Zone Type Grid Solution Structured 2 2 w If MHD If TURB 5 Figure 8 1 The Layout of AEROFLO Data in CGNS File Format More information can be obtained at http www cgns org WhatIsCGNS html Software for viewing or converting CGNS files can be do
37. flow conditions accuracy requirements and available computational resources If a high order calculation is preferred WENO 5 order or Compact 97 6 order spatial schemes should be used The MUSCL scheme is appropriate for low order second order accuracy If the flow speed is high the WENO scheme should be used The Compact scheme works well for subsonic flows The Runge Kutta method is 4 order accurate but is generally very expensive and has poor stability performance The Beam Warming 2 order method can provide fast convergence Sub iterations can be used to ensure time accurate calculations Good iteration time step sizes should be selected If the time step size is too large the sub iteration calculations may not converge If it is too small the sub iteration calculations may take too long to converge 98 14 Parallel Computation in AEROFLO This chapter introduces the implementation of a parallel calculation in AEROFLO 14 1 Running in Parallel Large problems can be solved in AEROFLO by using the parallel calculation technique Parallel calculation in AEROFLO is done by using the domain decomposition For multi block problems each block is sent to a parallel process Aside from the use of multi blocks there are no other requirements for modifying grid and project files for parallel calculations As long as MPICH or MPIPRO is installed on the user s parallel machines the user can simply start parallel calculations
38. for the multi block problems To run a parallel calculation under the command line environment simply type mpirun np mpiaeroflo lt project file name where n is the number of processes Before you run this command make sure your directory is where the project file is located and that both the parallel AEROFLO solver mpiaeroflo exe and the MPICH launch program mpirun exe can be found by your operating system in this directory If not you can simply copy these two commands from their installation directories to your project directory or add their directories to the PATH system environment variable Note AEROFLO multi block problems must be run in parallel mpiaeroflo exe Parallel calculations do not have to be run on a parallel machine For a single PC if MPICH 15 installed MPICH will automatically simulate the parallel environment which allows you to run multi block problems using more than one process restart a parallel calculation the same number of processes is required 14 2 An Example of a Parallel Calculation in AEROFLO We will still use the flow through converging diverging duct problem for a sample parallel calculation in AEROFLO In this case the grid we used in Chapter 5 is split into 2 blocks The sizes of the both blocks are 41x51 The 2 block grids are shown in Figure 14 1 99 Block 1 Coupling Boundary Block 2 Figure 14 1 Computational Grid for 2 Block Converging Diverging Duct Pr
39. format in AEROFLO is supported by most grid generation and CAD CAE software The following are some commercial software that are supported by AEROFLO GRIDGEN ICEM CFD VGRID Detailed information about the grid format in AEROFLO will be discussed in Chapter 8 3 3 Setting Up an AEROFLO Project The input parameters for AEROFLO are stored in a single project file To set up an AEROFLO project the user must provide the following information Simulation type eg general CFD MHD combustion aeroacoustics etc Grid information Physical models e g turbulence model combustion model etc Global flow conditions e g Mach number Reynolds number etc Boundary conditions Initial conditions Numerical schemes spatial differentiation and time integration schemes Output controls A project file can be created using AEROFLO s graphical user interface GUI or can be directly edited as a text file Chapters 5 and 6 will introduce how to create project files using the AEROFLO GUI and how 18 to directly edit them 3 4 Running an AEROFLO Project After the grid is created and the project file is set up the project can immediately be run in the AEROFLO GUI or in a command line The governing equations are solved iteratively A number of iteration steps are required to obtain convergent results The user can monitor the iteration residues to see if the calculation is converged A detailed procedure
40. install MPICH and click Next Choose Destination Location Setup will install MPICH in the following folder To install to this folder click Next To install to a different folder click Browse and select another folder en can choose not to install MPICH by clicking Cancel to exit etup Destination Folder C Program Files MPICH Browse lt Back Cancel Click Next Select Components Select the components you want to install clear the components you do not want to install Components runtime dlls 2584 Description This component contains the dlls necessary Change to run mpich applications It must be installed each machine Space Required 11656 K Space Available 3198488 lt Back Next gt e Click Next 10 Start Copying Files Setup has enough information to start copying the program files If you want to review or change any settings click Back If you are satisfied with the settings click Next to begin copying files Current Settings Destination C Program Files MPICH Back Cancel e Click Next cAprogram files mpich mpd bin mpirun exe More information about the installation of MPICH can be found on the MPICH website 2 After installing MPICH you may now install AEROFLO Unzip the installation file to any temporary folder You may need unzipping software s
41. need to modify your project file then run the problem using the modified project file The methods of using these two kinds of files to restart a 62 calculation are described below gt Restarting from the CGNS output file 1 Change the input meshfile for all the blocks to the single output CGNS file myres cgns 2 Change the filetype for each block to CGNS gt Restarting from the AEROFLO output files 1 Change the input meshfile for each block to the output AEROFLO file for each block 2 Change the filetype for each block to AEROFLO 7 3 Example of Modifying and Restarting a Calculation If the user wants to restart the previous calculation but also wishes to change the models schemes or other input parameters the user can first do the corresponding change in the project file and then follow the steps in Section 7 2 to restart the calculation Here we still use the converging diverging duct flow problem as an example to see how to modify a project file and restart a previous calculation Assume that you have finished the previous calculation 10 000 steps and you wish to do the following changes to obtain better results Change the turbulence model to Spalart Allmaras Change the spatial scheme to WENO scheme Change the time step size to 0 005 Change the output frequency to 200 steps Recalculate for 5000 steps To implement the above changes you can change the project file by using the GUI
42. of how to run and restart an AEROFLO calculation will be given in Chapter 7 3 5 Plotting Results AEROFLO outputs the simulation results at a frequency determined by the user The format of the output file may be TECPLOT PLOT3D or CGNS Note that AEROFLO does not provide post processing and visualization tools The user has flexibility in choosing any CFD visualization software to plot the results The following are some commercial software that can process AEROFLO output files TECPLOT FIELDVIEW Chapter 9 will introduce the details of outputting files 3 6 Revision and Recalculation After you get the calculation solution you may find that the solutions do not achieve your modeling goals This may be because computational domain is too small or the grids are not fine enough physical models you chose are not appropriate e g turbulence models boundary and initial conditions are not correctly set numerical schemes are not appropriate 19 If any of these is true you may need to change the grid file or revise the input parameters in the project file and recalculate the problem 20 4 AEROFLO s Graphical User Interface GUI The User Interface of AEROFLO provides an easy and visualizable way to set up the input parameters for an AEROFLO project This chapter introduces the basic components of AEROFLO s Graphical User Interface GUI To start the AEROFLO GUI program yo
43. on Spalart Allmaras model Partially Resolved Numerical Simulation PRNS based on Abid s model RANS is the most popular turbulence simulation approach in the industry due to its simplicity and relatively low computational cost However it is the least accurate DNS on the other hand provides very accurate turbulence results since it can resolve all scales but is only limited to very low Reynolds number calculations because of its high computational cost LES provides more accurate results than RANS is also more computationally intensive but costs less to simulate compared to DNS 93 The selection of turbulence models is based on the flow characteristics the simulation accuracy requirement and the available computation resources Also different turbulence models have different requirements for the computational grids For instance high accuracy turbulence models often times cannot use coarse grids The selection of turbulence models for RANS is also influenced by the flow boundary treatments For example if accurate near wall flow structures are important the grids close to the wall must be fine and low Reynolds number models are preferred If the near wall flow structures are not important and the grids close to the wall are coarse it is then more appropriate to use high Reynolds number turbulence models 94 13 Numerical Schemes This chapter is a basic introduction to the numerical differencing schemes used in AE
44. simulation types SIMTYPE 5 or 6 case specific data for certain internally constructed problems output and animation generation data specification of points at which to print out visual solution data Keywords of block scope include BLOCK FACEBC LINEBC NODEBC SINITIAL specifies a mesh block This keyword provides data such as the dimensions of the mesh location of the grid file and initial condition file as well as a unique name for the block This input group may appear several times Each occurrence specifies a unique mesh block All projects require the specification of at least one block specifies a surface boundary condition specifies a line boundary condition specifies a boundary condition on nodes applies initial conditions to blocks 115 Keywords used to overset specifications POINT used to define a geometric point in the project BOX used to define a box in space for blanking of regions MESHCUT used to define a region of or more blocks that will be blanked by another block OVERSET specification of overset variables Not mandatory 16 1 GLOBAL Keywords The sub keywords in the GLOBAL keyword block specify the global project data including simulation type project folder project files and flow parameters such as Reynolds number Mach number etc For most projects this block may be mandatory because the flow parameters are required TITL
45. the computational grid will be shown Set Boundary Conditions Boundary conditions must be specified at all of the grid boundaries The following steps describe how to set the boundary conditions for each of the boundary faces The boundary conditions are summarized in Table 5 1 a Inlet I 1 face Select First I Face in the BC on Blocks drop down menu The inlet boundary face is highlighted white colored in the Graphics Display dialog box To add the u boundary condition Click the Add Boundary Condition button to open the Add New BC dialog box In the Type drop down menu select Dirichlett In the Variable drop down menu select u velocity In the Value input box type 1 0 Click OK to close the Add New BC dialog box VV ON ON ON To add the v 0 boundary condition Click the Add Boundary Condition button to open the Add New BC dialog box gt Inthe Type drop down menu select Dirichlett gt In the Variable drop down menu select v velocity gt In the Value input box type 0 0 45 gt Click OK to close the Add New BC dialog box To add the p boundary condition VV VV V Click the Add Boundary Condition button to open the Add New BC dialog box In the Type drop down menu select Dirichlett In the Variable drop down menu select Density In the Value input box type 1 0 Click OK to close the Add New BC
46. to Range in K 0 to Select other block and other face and range Figure 4 9 Add Modify BC Dialog Box 30 Initial Conditions button This button opens the Initial Condition dialog box which is used to specify the global initial condition This initial condition is applied to all the nodes of the indicated block or blocks Figure 4 10 is a screen shot of the Initial Condition dialog box The Block drop down menu is used to select the block s to which an initial condition is being applied The Add New Initial Conditions and Modify Selected Initial Conditions buttons open up the New Initial Condition Modify Initial Condition Dialog Box that allows you to specify or modify a global initial condition on a variable The Delete Selected Initial Conditions button deletes a selected initial condition Initial C All blocks Add New Initial Conditions Modify Selected Initial Conditions Delete Selected Initial Conditions Close Figure 4 10 Initial Conditions Dialog Box Figure 4 11 is a screen shot of the New Initial Condition Modify Initial Condition dialog box The Variable drop down menu is used to select the variable to which an initial condition applies The Value input box is used to specify the initial condition value 31 Help New Initial Condition Value 0 00000 00 Figure 4 11 New Initial Condition Modify Initial Condition Dialog Box Time Integration Scheme button This button opens up a Time Integr
47. variable in the equation expression The values of VARI are as follows 1 5 Ju E y 6 3 7 7 nstep 4 M 4 w 5 p IOBCS IOBCE The start and end nodal points in i for a boundary lying in the i j or k i planes for the block to which the current block is supplied The default values are 1 and IE respectively for the block to which the current block is supplied JOBCS JOBCE The start and end nodal points in j for a boundary lying in the i j or j k planes for the block to which the current block is supplied The default values are 1 and JE respectively for the block to which the current 137 block is supplied KOBCS KOBCE The start and end nodal points in for a boundary lying in the j or i planes for the block to which the current block is supplied The default values are 1 and KE respectively for the block to which the current block is supplied OPERATOI The arithmetic operation in a boundary condition specified in equation form TYPE 80 VALI The sub keyword is used in conjunction with the sub keywords VARI and OPERATO to apply simple equations of the boundary The simple equation format of the boundary condition type 80 is VAR VAL1 OPERATO1 VAR1 The format of the equations is OPERATOI Equation VAL VARI VALI VAL VARI VALI VAL VARI VALI VAL VARI VALI Tu VAL VARI VALI ABS VAL ABS VAR1
48. 0 Click OK to close the New Initial Condition dialog box To specify the P 3 37564 initial condition Click the Add New Initial Conditions button to open the New Initial Condition dialog box In the Variable drop down menu select Pressure In the Value input box type 3 37564 Click OK to close the New Initial Condition dialog box Click Close to close the Initial Conditions dialog box and return to the main graphical interface Note If you set the above initial conditions incorrectly and wish to modify them you can select the initial condition that you wish to modify in the initial condition list and click Modify Selected Initial Conditions to modify it You can also use Delete Selected Initial Conditions to delete the wrong initial condition and create a new initial condition to replace it 11 Set Time Integration Scheme 12 For this problem the Beam Warming scheme is used for time integration The time step size is set to 0 01 and the problem will be calculated for 10 000 steps Use the following steps to set the time integration scheme a b d e f Click the Time Integration Scheme button to open the Time Integration Scheme dialog box In the Time Scheme drop down menu select BW2 Full Formulation Make sure that the Use the fixed time steps button is selected Also check to make sure that the Use preconditioner button is not selected In the Max
49. 00000 3000000 0 3000000 ALPHAL 0000000 00 0000000 00 0 0000000E 00 ALPHA2 3000000 3000000 0 3000000 ALPHA3 3000000 3000000 0 3000000 ALPHA4 3000000 3000000 0 3000000 5 3000000 3000000 0 3000000 ORDERN 10 10 ORDER1 0 0 ORDER2 ORDER3 ORDER4 ORDERS o0 00 44 oo MM OMM oM 44 1 NNNN 2 2 2 2 2 2 2 2 MM OM MM M M M oM o9 SEND SOUTPUT 4 2 PRINTFRQ 200 Change PRINTFRQ 0200 Output FORMAT TECPLOT SEND Frequency SDEBUG POINT 2 2 5 2 Figure 7 1 Revised Project File for Flow Through Converging Diverging Duct 65 SEND SBLOCK NAME MESHFILE FILETYPE ICFILE PERIODIC ISIZE JSIZE KSIZE ORDER ANGLE DISTANCE NOCROSS SEND mesho myres cgns CGNS or NULL MESHFILE mesh0 tmp FILETYPE AEROFLO H H 0 81 51 1 2 0 0000000E 00 0 0000000E 00 0 Change MESHFILE to myres cgns and FILETYPE to CGNS or change 3 MESHFILE to mesh0 tmp and FILETYPE to AEROFLO COMMENT FACEBC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND COMMENT SFACEBRC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND COMMENT SFACERC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISP
50. 0891 42nd AIAA Aerospace Sciences and Exhibit Reno NV 5 8 January 2004 Cai X amp Ladeinde F 2004 A Unified Computational Methodology for Rarefied and Continuum Flow Regimes AIAA Paper 2004 1178 42nd AIAA Aerospace Sciences and Exhibit Reno NV 5 8 January 2004 Ladeinde F Cai X Visbal M R amp Gaitonde D 2003 Parallel Implementation of Curvilinear High Order Formulas nt Journal of Computational Fluid Dynamics Vol 17 6 pp 467 485 Ladeinde F Cai X Visbal M R amp Gaitonde D 2001 Turbulence Spectra Characteristics of High Order Schemes for Direct and Large Eddy Simulation J Applied Numerical Mathematics Vol 36 2001 pp 447 474 Ladeinde F Cai X Visbal M R amp Gaitonde D 2001 Parallel Computation of Complex Aeroacoustic Systems AIAA 2001 1118 39th Aerospace Sciences Meeting and Exhibit Reno NV Ladeinde F Cai X Sekar B amp Kiel B 2001 Application of Combined LES and Flamelet Modeling to Methane Propane and Jet A Combustion AIAA 2001 0634 39th Aerospace Sciences Meeting and Exhibit Reno NV Ladeinde F Cai X and Sekar B 2000 Flamelet Studies of Reduced and Detailed Kinetic Mechanisms for Methane Air Diffusion Flames Paper 2000 GT 0144 Proceedings of IGTI ASME TURBO EXPO 2000 May 8 11 2000 Munich Germany 155 30 31 Ladeinde F Cai X Visbal M R amp Gaitonde D 2000 Studies of DRP and Compact Schemes for Aeroacoustic Simulation
51. 1 POINT Integer Array 3 TE 2 JE 2 KE 2 1 IE JE KE NFIELDS Integer 0 IFIELD Integer 1 10 1 to NFIELDS SINITIAL Keyword Data Type Default Value Range Required BLOCK Character All blocks Block names VARIABLE Integer 1 8 YES VALUE Real 0 0 151 BLOCK VARIABLES BLOCK Keyword Data Type Default Value Range Required NAME Character 40 YES MESHFILE Character 80 YES FILETYPE Character 40 AEROFLO CGNS AEROFLO PLOT3D ICFILE Character 80 SS ISIZE Integer YES JSIZE Integer YES KSIZE Integer YES PERIODIC Integer array 3 0 0 0 0 1 2 Following input required only for multi block formulation DONORS Character array Block names ORDER Integer GLOBAL ORDER ANGLE Real 0 0 DISTANCE Real 0 0 FACEBC Keyword Data Type Default Value Range Required BLOCK Character Block names YES SIDE Integer 1 6 YES TYPE Integer 0 100 YES VALUE Real 0 0 VARIABLE Integer 1 8 Depends on TYPE DEPTH Integer BLOCK ORDER ISPLANE Integer 1 ISNORMAL Integer 1 5 Integer 1 Integer BLOCK ISIZE JBCS Integer 1 Integer BLOCK JSIZE KBCS Integer 1 Integer BLOCK KSIZE CNORM Real Array 0 0 0 0 0 0 OBLOCK Character Block names OSIDE Integer 1 6 VARI Integer 7 3 VALI Integer OPERATOI Character 40 xy ABS INT ATAN SIN COS EXP IOBLS Image IOBCE Image JOB
52. 167 ELECPOT Real Array 1 NUMELEC CASE 167 SLOPE Real INTERCPT Real MACH2 Real P2PI Real RHO2RHOI Real FLDEFAN Real POISSON Keyword Data Type Default Value Range Required NUMITER Integer 0 FREQ Integer 0 PRINTFRQ Integer 0 RELAXER Real 0 0 ALPHALIM Real Array 2 0 0 MVL Integer 0 IFILTER Integer 0 0 1 SFILTER Integer Array 3 0 EFILTER Integer Array 3 YES GAUSS Integer 1 SIGMIN Real 0 0 SIGFAC Real 0 0 SIGDEF Real 0 0 COMPACTB Character YES ALPHAN Real 0 0 0 0 0 499 ALPHA Real 0 0 0 0 0 499 ALPHA2 Real 0 0 0 0 0 499 ALPHA3 Real 0 0 0 0 0 499 ALPHA4 Real 0 0 0 0 0 499 ALPHAS Real 0 0 0 0 0 499 ORDERN Integer 10 1 10 150 Integer 0 ORDER2 Integer 2 ORDER3 Integer 4 ORDER4 Integer 6 ORDERS Integer 8 OUTPUT Keyword Data Type Default Value Range Required PRINTFRO Integer 100 FORMAT Character CGNS TECPLOT PLOT3D MOVIEON Integer 0 0 1 Integer IRANGE Integer Array 3 LIE I JRANGE Integer Array 3 1 JE 1 KRANGE Integer Array 3 1 KE 1 FILENAME Character aeromv GRIDNAME Character aeromv grid TECANIM Integer 0 0 1 TRANGE Integer Array 3 0 0 MAXITER ENTROPY Integer 0 0 1 IPERPROC Integer 0 0 1 DEBUG Keyword Data Type Default Value Range Required WRITONLY Integer 0 0
53. 2 An Example of a Parallel Computation in AEROFLO 14 3 Automatic Domain Decomposition 14 4 Automatic Determination of Interior Block Interface 15 Performing Overset Calculations 15 1 Basic Multi Block Calculations with Coincident Node Overlap 15 2 Overset Multi Block Calculations with Non Coincident Node Overlap 15 3 Mixed Block Calculations 15 4 Specifying Blank Regions 16 AEROFLO Input Keywords 16 1 SGLOBAL Keywords 16 2 STURB Keywords 16 3 SSPATIAL Keywords 16 4 STIMESTEP Keywords 16 5 DAMPING Keywords vi 89 89 89 9 92 92 93 95 95 95 97 97 98 99 99 106 106 107 107 111 112 113 115 116 118 120 124 127 16 6 SOUTPUT Keywords 16 7 DEBUG Keywords 16 8 SBLOCK Keywords 16 9 SFACEBC Keywords 16 10 SINITIAL Keywords 16 11 SOVERSET Keywords 16 12 MESHCUT Keywords 16 13 SPOINT Keywords 16 14 Box Keywords FAQ Summary of AEROFLO Keywords AEROFLO Papers Reference vii 129 131 132 135 139 140 142 143 144 145 146 154 157 1 Introduction AEROFLO is a high order multi disciplinary computational fluid dynamics CFD solver package developed by TTC Technologies It is the first commercial high order multi disciplinary CFD simulation software that can solve flows with complex geometries at all speeds 1 1 The Purpose of AEROFLO With the rapid development of computer hardware techniques many commercial CFD software packages have been developed that enable users to easi
54. AA Paper 2007 826 45th AIAA Aerospace Sciences Meeting and Exhibit Reno NV 08 11 2007 Ladeinde F Alabi K Safta C Cai X Johnson F 2006 The First High Order CFD Simulation of Aircraft Challenges and Opportunities AIAA Paper AIAA 2006 1526 44th AIAA Aerospace Sciences Meeting and Exhibit Reno NV Jan 08 11 2006 Safta C Alabi K Ladeinde F Cai X Kiel B Sekar B 2006 Comparative advantages of high order schemes for subsonic transonic and supersonic flows AIAA Paper AIAA 2006 299 44th AIAA Aerospace Sciences Meeting and Exhibit Reno NV Jan 08 11 2006 Safta C Alabi K Ladeinde F 2006 Level Set Flamelet Large Eddy Simulation of a Premixed Augmentor Flame Holder Paper AIAA 2006 156 44th Aerospace Sciences Meeting and Exhibit Reno NN Jan 08 11 2006 154 14 15 16 17 18 19 20 21 22 23 24 25 26 21 28 29 Ladeinde F Safta C Sekar B Lynch A and Kiel B 2005 Validation of Advanced Large Eddy Simulation Methods for Augmentor Applications 53rd Joint Army Navy NASA Air Force JANNAF Meeting Monterey CA Cai X and Ladeinde F 2006 An Evaluation of the Partially Resolved Numerical Simulation Procedure For Near Wall Performance AIAA 2006 0115 The 44th AIAA Aerospace Sciences Meeting and Exhibit 9 12 January 2006 Reno Nevada Safta C Alabi K and Ladeinde F 2005 Comparative advantag
55. AEROFLO User s Manual TTC Technologies Inc P O Box 1527 Stony Brook New York 11790 May 2 2006 July 1 2007 October 3 2007 February 5 2008 1993 2008 Copyright TTC Technologies Inc Preface What is in This Manual The Standard AEROFLO User s Guide contains the following Basic overview of the AEROFLO Multi Disciplinary Software Software installation guide Introduction to the user interface GUI Detailed procedures for performing general CFD simulations in AEROFLO Tutorial of simple CFD simulation Physical models used in AEROFLO Numerical models used in AEROFLO M Parallel calculations in AEROFLO Keyword reference What is in the Other Manuals In addition to the AEROFLO User s Guide there are other manuals available to help you use AEROFLO ii AEROFLO CFD Sample Problems provide sample problems for AEROFLO CFD computation in AEROFLO AEROFLO Technique Reference provides a detailed technical reference for the physical and numerical models used in AEROFLO AEROFLO MHD Manual describes how to use AEROFLO to perform a magnetohydrodynamic simulation AEROFLO Aeroacoustics Manual describes how to use AEROFLO to simulate and analyze the acoustic generation by aerodynamic flows AEROFLO Combustion Manual contains the models and procedures used to simulate turbulent reacting flows AEROFLO Hypersonic Flow Manual describes how to simulate non equilibrium hypersonic flows
56. ARIABLE VALUE Neumann Type 23 Flux Type 24 9 _ dr 0 for type 23 On fis some real number Specifying this boundary condition requires the following BLOCK SIDE 84 TYPE VARIABLE VALUE for type 24 11 2 2 Compound Boundary Conditions Solid Wall Type 1 Dirichlett f 0 0 for w velocity Neumann for density pressure Specifying this boundary condition requires the following BLOCK SIDE TYPE Symmetry Type 11 13 14 15 Slip Type 71 D Neumann for density pressure 0 0 n Tangential velocity aa 0 n Normal velocity gen 0 Specifying this boundary condition requires the following BLOCK SIDE TYPE Axisymmetry Type 60 61 62 Inflow Type 30 Dirichlett neg f for u v w velocity Neumann for density pressure Note that the inflow boundary condition assumes that the flow is normal to the surface When this is not 85 the case e g the flow has an angle of attack relative to the inflow surface use Dirichlett on each velocity variable Specifying this boundary condition requires the following BLOCK SIDE TYPE VALUE Outflow Type 31 09 Neumann for all variables E 0 n V 0 n Specifying this boundary condition requires the following BLOCK SIDE TYPE Free Stream Type 32 09 Neumann for all variables D 0 n V 0 n Specifying this boundary condition requires th
57. ATIAL TIMESTEP and BLOCK and others are optional such as TURB and DAMPING In each block the input parameters are set by assigning a specified value or data to a special keyword For example the Mach number 0 42 is assigned to the keyword MACH by a statement MACH 0 4200000 Each of the blocks contains several of these value assignable keywords These keywords are called sub keywords Under each of the group keywords the block contains its own special group of sub keywords The meaning of some primary sub keywords and the meaning of their values are explained in the comments in Figure 6 1 In this project file the first block is 6LOBAL which sets the global project data including the project title project subfolder simulation type and flow parameters Ma Re Pr The next block is block which is used to set the overall boundary condition information In this case no overset boundary condition is used Therefore there is no sub keyword is assigned inside this block The TURB block sets the turbulence modeling the SPATIAL block sets the spatial differencing scheme and the TIMESTEP block sets the time differencing scheme The DAMPING block contains the spatial scheme damping and filtering information which is not used in this project The OUTPUT block sets the output format and frequency while the DEBUG block is the diagnostic point at which visual solution data can be printed out One BLOCK block
58. CS Image JOBLE Image KOBCS Image KOBLE Image 152 SOVERSET Keyword Data Type Default Value Range Required TYPE Integer 0 0 1 RESTART Integer Array 3 0 0 2 COINNODE Integer 0 0 1 PROJECT Integer 0 0 1 NUMITER Integer 2 HSEADT Integer 1 0 1 POINT Keyword Data Type Default Value Range Required COORDS Real array 3 YES BOX Keyword Data Type Default Value Range Required POINTS Integer Array 8 Point list YES BLOCKS Character array Block name list YES MESHCUT Keyword Data Type Default Value Range Required CUTTER Character 40 Block name list YES BLOCKS Character array Block name list YES ORDER 2 PERIODIC Integer Array 0 0 0 0 5 153 10 11 12 13 AEROFLO Papers Cai X D amp Ladeinde 2005 Comparative Studies of Two POD Methods for Airfoil Design Optimization In Computational Fluid and Solid Mechanics 2005 Edit K J Bathe Science Publishers Amsterdam The Netherlands pp 1227 1230 Cai X amp Ladeinde F 2001 Performance of Sub grid Flamelet Model in LES of Reacting Turbulent Flows In DNS LES Progress and Challenges Greyden Press Columbus Ohio Edit C Liu L Sakell amp T Beutner pp 299 310 Ladeinde F Cai X Ramons R A amp Schlinker R H 2008 On the Connection between Near field and Far field Solutions of High Subsonic Jet Noi
59. Character SIMTYPE Integer 2 1 7 FOLDER Character MACH Real REYNOLDS Real ORDER Integer 2 STORAGE Integer 1 0 1 TURB Keyword Data Type Default Value Range Required TURBITY PE Integer 0 0 5 DIRECTN Integer Array 3 0 TURBTYPE 4 NUMTRIPS Integer 0 TURBTYPE 5 POINT Integer Array 3 1 to NUMTRIPS PLANE Integer Array 3 1 3 146 MHD Keyword Data Type Default Value Range Required LORSIG Character NULL BRDOCOMP Character NULL ESOLVE Character NULL MHDPRES Real MHDREYN Real RINTERCT Real HALLPARM Real IONSPARM Real JOULEHT Real SPATIAL Keyword Data Type Default Value Range Required SCHEME Integer Array 3 YES METRIC Integer YES VISCOUS Integer Array 3 0 0 0 VISCHEME Integer 0 VISCMON Integer 0 SUTHERLN Real 10000 COMPACTI Character 20 If SCHEME 1 is 15 COMPACTJ Character 20 If SCHEME 2 is 15 COMPACTK Character 20 If SCHEME 3 is 15 COMPACTG Character 20 If METRIC is 1 2 or 12 CUTOFFI Real If SCHEME 1 is 1 5 CUTOFFJ Real If SCHEME 2 is 1 5 CUTOFFK Real If SCHEME 3 is 1 5 ISOTROPI Integer ISOTROPJ Integer ISOTROPK Integer ICUT Integer Array 3 JCUT Integer Array 3 KCUT Integer Array 3 PERIODIC Integer Array 3 0 0 0 0 1 BLOCK Character 40 Block names 147
60. E This input specifies a title for the simulation for informational purposes SIMTYPE The type of simulation 1 4 DNS LES 5 6 MHD MACH Mach number for the simulation REYNOLDS Reynolds number for the simulation ORDER Specifies how many nodes at a boundary will be applied to a boundary condition FOLDER Folder from which input files grid and initial condition file will be read and in which output files will be generated When not specified the AEROFLO folder will be used as the project folder For organizational purposes the user should create separate folders for each project as subfolders of the main AEROFLO folder 116 The included sample problems are organized in this manner STORAGE Specifies if all processors for a multi block calculation have a shored storage If so the storage takes a value of 1 which is its default value Otherwise its value is 0 117 16 2 TURB Keywords The sub keywords in the TURB keyword block specify turbulence data This keyword block is not mandatory When not provided no turbulence model is activated for the problem TURBTYPE Turbulence model Available options include 0 No turbulence model is used Laminar Turbulent DNS or MILES 1 Smagorinsky with compact differencing of the turbulence equations 2 Smagorinsky with 2 9 central differencing of the turbulence equations 3 Smagorinsky with 1 differencing of the turbulence equa
61. ECANIM is 1 see TECANIM below myres dat tecplot result file is generated Cp dat tecplot result file is generated for all wall boundaries Intermittent tecplot result files are generated with names resi dat if TECANIM is 1 see TECANIM below myres cgns result output restart file is generated myres PLOT3D and myres PLOT3DQ PLOT3D grid and Q result file are generated Intermittent PLOT3D Q result files are generated with names res1 3dq if TECANIM is 1 see TECANIM below myres cgns result output restart file is generated This variable determines if complete result files will be intermittently written and stored Takes on a value of 0 or 1 TRANGE The range in time at which the intermittent result files will be written 129 TRANGE 20000 40000 2 The above specification will cause result files to be written between the 20 000 and 40 000 iterations at every 2 PRINTFRQ iteration To print the initial conditions the TRANGE start should be 0 130 16 7 DEBUG Keywords The sub keywords in the DEBUG keyword block define the points at which to print out visual solution data These are not mandatory POINT A point in the block at which visual diagnostic results are printed at every sub iteration If not provided diagnostic values are printed at the center of the block IE 2 JE 2 KE 2 POINT 20 4 2 The above specification will cause diagnostic results to be printed at node 20 4 2 131 16 8
62. EPTH 9 BLOCK2 i y 23 10 BLOCK2 zi 23 Block 1 is coupled with block 2 in last face Block 2 is coupled with block 1 in first face Figure 14 2 The Project File cdvductm afl for Flow Through Converging Diverging Duct two Block Cont 103 ISPLANE 0 ISNORMAL 15 SEND COMMENT BC 11 FACEBC BLOCK BLOCK2 SIDE 1 23 VARIABLE d DEPTH 22 ISPLANE 0 ISNORMAL d SEND COMMENT BC 12 SFACEBRC BLOCK BLOCK2 SIDE 1 10 VARIABLE VALUE 3 263250 DEPTH 245 ISPLANE 0 ISNORMAL ds SEND COMMENT BC 13 FACEBC BLOCK BLOCK2 SIDE 2 5 TYPE Isy DEPTH 2 5 ISPLANE ISNORMAL l1 SEND COMMENT BC 14 FACEBC BLOCK BLOCK2 SIDE 2 TYPE 1 DEPTH 25 ISPLANE 0 ISNORMAL SEND M m SINITIAL VARIABLE 2 VALUE 1 000000 SEND SINITIAL VARIABLE 35 VALUE 0 0000000E 00 SEND SINITIAL VARIABLE d VALUE 1 000000 SEND SINITIAL VARIABLE Er VALUE 3 375640 SEND Figure 14 2 The Project File cdvductm afl for Flow Through Converging Diverging Duct two Block Cont 104 Two Blocks Ma 0 08 0 16 0 24 0 33 0 41 0 49 0 57 0 65 0 73 0 82 0 90 0 98 1 06 1 14 1 22 Single Block Ma 0 08 0 16 0 24 0 33 0 41 0 49 0 57 0 65 0 73 0 82 0 90 0 98 1 06 1 14 1 22 Figure 14 3 Mach Number Contour for the
63. ES2 0 2000000 54 9 9999998E 03 FES2 FES4 MAXRE OMGAV SRCON FILTE NFILT ALPHAN ALPHA ALPHA ALPHA ALPHA ALPHA ORDERN ORDER ORDER ORDER ORDER ORDER SEND 1 000000 2 000000 I 9 9999998E 03 ST 0 0000000E 00 0 0 0 1 1 0 3000000 3000000 3000000 0000000 00 0000000 00 0000000 00 3000000 3000000 3000000 3000000 3000000 3000000 3000000 3000000 3000000 3000000 3000000 3000000 10 10 0 0 1 2 3 4 5 GERGEN EN KREE EN lt gt EEN lt 4 4 1 2 3 4 5 LA NNNN OO MM OM UM GM GM M oM oM MOM OM UM GM GM 2 2 2 2 2 2 2 2 GLOBAL Global Project Data OVERSET Overset Variables TURB Turbulence Data SPATI AL Spatial Differencing Data TI MESTEP Time Differencing Data DAMPI NG Damping or Filtering Data Figure 6 1 The Project File cdvduct afl for Flow Through Converging Diverging Duct 52 SOUTPUT PRINTFRQ FORMAT SEND DF ae Output Frequency 9e enne am etate een Output Format SDEBUG POINT SEND SBLOCK NAME mesh ee Mesh Block Name MESHFILE FILETYPE ICFILE PERIODIC ISIZE JSIZE KSIZE ORDER ANGLE DISTANCE NOCROSS SEND mesh 001 4 PLOTSD psoas ess Ee Mesh File Name PLOT3DF
64. HD SIGTYPE Character If MHD SIGCOMP Character If MHD NGAUSS Integer If MHD AMPGAUSS Real Array IGAUSS Integer Array EPSGAUSS Real Array DELGAUSS Real Array XCTR Real Array YCTR Real Array ZCTR Real Array If MHD REFTEMP Real If MHD RINDEX Real If MHD RKVL Real CASE 31 39 OMEGA Real CASE 61 67 AVALUE Real LEADEDGE Integer CASE 11 701 800 YSURFACE Real CASE 81 ZSURFACE Real CASE 91 99 111 MAXRED Integer CASE 111 NUMDIPS Integer CASE 111 161 166 168 170 XDIPLOCS Real Array 1 NUMDIPS YDIPLOCS Real Array CASE ZDIPLOCS Real Array 111 161 166 168 170 IDIPCOL Integer Array 1 NUMDIPS CASE 111 DIPNORM Integer CASE 167 RXDIP Real Array 1 NUMDIPS RYDIP Real Array CASE 161 166 168 170 RZDIP Real Array RMAGDIPS Real Array EUNIFX Real Array CASE 131 EUNIFY Real Array EUNIFZ Real Array BUNIFX Real Array BUNIFY Real Array BUNIFZ Real Array 149 IRAMP Integer CASE 141 ICOWL Integer ISWST Integer ISWND Integer ICOMND Integer STRIPSGN Integer STRIPSAC Integer UFIXD Real CASE 151 155 VFIXD Real WFIXD Real BXFIXD Real BYFIXD Real BZFIXD Real TILTANG Real NUMELEC Integer CASE 153 154 167 ELECST Real Array 1 NUMELEC ELECND Real Array CASE 153 154
65. LANE ISNORMAL SEND COMMENT SFACEBRC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND COMMENT SFACEBC BLOCK SIDE TYPE VARIABLE DEPTH ISPLANE ISNORMAL BC BC BC BC BC H LA mesh0 LA 0 0000000E 00 mesho ll r 1 000000 e meshO0 3 375640 N D m Block Data to Restart Files Figure 7 1 Revised Project File for Flow Through Converging Diverging Duct Cont 66 SEND COMMENT SFACEBC BLOCK SIDE TYPE VARIABLE DEPTH ISPLANE ISNORMAL SEND COMMENT SFACEBC BLOCK SIDE TYPE VARIABLE DEPTH ISPLANE ISNORMAL SEND COMMENT SFACEBC BLOCK SIDE TYPE VARIABLE VALUE DEPTH ISPLANE ISNORMAL SEND COMMENT SFACEBC BLOCK SIDE TYPE DEPTH ISPLANE ISNORMAL SEND COMMENT SFACEEC BLOCK SIDE TYPE DEPTH ISPLANE ISNORMAL SEND BC BC BC BC BC SINITIAL VARIABLE VALUE SEND SINITIAL VARIABLE VALUE SEND SINITIAL VARIABLE VALUE SEND SINITIAL VARIABLE VALUE SEND mesh0 1 23r LA Se m m mesho 1 10 3 263250 m 1 000000 21 0 0000000E 00 12 1 000000 e 5 3 375640 Figure 7 1 Revised Project File for Flow Through
66. NSION IL JL KL X Y Z U V W RHO P Generate the mesh of size IL JL KL OPEN 2 FILE test in FORM UNFORMATTED status REPLACE TINIT 0 0 WRITE 2 IL JL KL O TINIT WRITE 2 X WRITE 2 Y WRITE 2 Z WRITE 2 U WRITE 2 V WRITE 2 W WRITE 2 P WRITE 2 RHO CLOSE 2 8 3 Right Hand Rule In AEROFLO the right hand rule must be obeyed by the grid coordinates x 2 and the grid indices 1 j The rule can be explained as following Imagine pointing the right hand index finger along the positive x or axis Then curl the rest of the right hand fingers toward the positive y or j axis The thumb pointing straight out is now in the positive z or k direction Figure 8 2 shows an example of the right hand system 74 k x i j Index direction Axis direction Figure 8 2 Right Hand System In AEROFLO the user can load 2D grids However all 2D grids will be converted to 3D grids inside AEROFLO by extruding the grids in the positive z direction That means the k indices direction is fixed to positive z direction for a 2D grids Therefore the 2D grids still need to follow the right hand rule Figure 8 4 shows example 2D grids that either obey or violate the right hand rule in AEROFLO UNE valid grid invalid grid
67. No of Steps input box type 10000 In the Time Step Size input box type 0 01 Click OK to close the Time Integration Scheme dialog box Set Spatial Differencing Scheme For this problem the MUSCL scheme is used for the spatial scheme and the 2 order central difference scheme is used for the metrics differencing scheme Use the following steps to set the spatial differencing scheme a Click the Spatial Differencing Scheme button to open the Spatial Differencing Scheme dialog box In the Simulation Type buttons select Viscous since the flow in this problem is considered to be viscous Select the Roe MUSCL scheme for both I and J directions 48 d Select Second Order Central scheme for Metrics e Click Close to close the Spatial Differencing Scheme dialog box 13 Set Spatial Damping Filtering For this problem there is no need to use spatial damping or filtering Use the following steps to set the spatial damping filtering scheme a Click the Spatial Damping Filtering button to open the Spatial Damping Filtering dialog box b Leave all the selections as default c Click Close to close the Spatial Damping Filtering dialog box 14 Set Turbulence Modeling For this problem the Abid s model is used for turbulence calculation Use the following steps to set the turbulence model Click the Turbulence Modeling button to open the Turbulence Modeling dial
68. PACTI 121 CUTOFFI Controls the entropy cutoff for the Roe scheme in the direction Used only if SCHEME 15 1 5 in the I direction CUTOFFJ Controls the entropy cutoff for the Roe scheme in the J direction Used only if SCHEME is 1 5 in the J direction CUTOFFK Controls the entropy cutoff for the Roe scheme in the K direction Used only if SCHEME is 1 5 in the K direction ISOTROPI Controls the choice of an isotropic or anisotropic formula in direction Used only if SCHEME is 1 5 in the I direction ISOTROPJ Controls the choice of an isotropic or anisotropic formula in J direction Used only if SCHEME is 1 5 in the J direction ISOTROPK Controls the choice of an isotropic or anisotropic formula in K direction Used only if SCHEME is 1 5 in the K direction ICUT Three variables that control the on off switches for the linear and u c eigenvalues respectively Used only if SCHEME is 1 5 in the direction For example ICUT 0 0 0 turns off all the switches for the eigenvalues JCUT Switches for J direction See notes for ICUT 122 KCUT Switches for K direction See notes for ICUT BLOCKS In certain calculations it is desired to use different spatial schemes for different calculations If BLOCK is specified the current SPATIAL specification applies to the block Otherwise the specification applies to all blocks If provided this refers to the block to which the spatial scheme specified in t
69. ROFLO are introduced Users are always advised to follow these procedures when using AEROFLO 3 1 Detailed Procedures Once you have determined the CFD problem you want to solve you can follow the basic procedures shown below Step 1 Step 2 Step 3 Step 4 Step 5 Generate computational grids Set up an AEROFLO project file Run the AEROFLO project Plot AEROFLO results Consider revisions to the grids and models if necessary Figure 3 1 is a flow chart of these procedural steps to solving a CFD problem in AEROFLO Each procedure is also discussed in the following section of this chapter 16 Select the computational domain with the boundaries 2 Provide the computational grids Need to revise Set the flow and solver simulation parameters parameters to create an AEROFLO project file 5 Specify initial conditions boundary conditions 2 Compute and monitor the solution 2 Need to revise grid Visualize the results 2 Recalculate the problem If necessary if revisions are necessary Figure 3 1 Basic Procedures for CFD Analysis in AEROFLO 17 3 2 Creating Grids AEROFLO currently only supports structured grids The input grid formats may be PLOT3D CGNS or AEROFLO format Note that AEROFLO does not provide the grid generation tools However the user has flexibility in choosing grid generation tools since the grid
70. ROFLO for solving the flow and or chemical species equations 13 1 Introduction of Numerical Schemes In AEROFLO the governing differential equations are solved by finite difference in a generalized curvilinear coordinate system Different spatial differencing and time integration schemes are used in AEROFLO which are summarized below 13 2 Spatial Differencing Schemes The parameters for the spatial schemes are set by using the SPATIAL keyword The following spatial schemes are supported by AEROFLO Inviscid Fluxes The inviscid flux terms which are the convective and pressure terms have a hyperbolic character This wave nature can be used to compute the flux with upwind methods Roe Schemes There are two representative upwind methods the flux differencing splitting method Roe s scheme and the flux vector splitting method van Leer s scheme The Roe scheme is based on characteristic wave disturbance and by design can capture stationary discontinuities It is less dissipative than the van Leer s scheme and is therefore better for boundary layer flows In the Roe scheme a flux difference term is added to the central difference scheme to account for the upwind effects To handle flow discontinuities e g shock wave a flux limiter is added to the extrapolation formulas to prevent a large gradient There are different kinds of Roe schemes due to the different format of extrapolation formulas AEROFLO includes the fol
71. Run the code by typing aeroflo and the program will request an input file lt lt C WINDOWS System32 cmd exe aeroflo Microsoft Windows XP Version 5 1 26001 lt C Copyright 1985 2001 Microsoft Corp C Documents and Settings Wenhaided c aerof lo test lo test gt Daerof lo enter the name of the be input file 5 Type ina project file name cdvduct afl C WINDOWS System32 cmd exe aeroflo Microsoft Windows Version 5 1 2666 lt C Copyright 1985 2661 Microsoft Corp C Documents and Settings Wenhaidcd c aerof lo test iC aerof lo test gt aerof lo enter the name of the be input file icduduct af lu 6 The program reads the input files and begins to run the calculation The log information of the calculation is output to the screen 61 cx C WINDOWS System32 cmd exe aeroflo iC aerof lo test gt aerof lo enter the name of the be input file icduduct af1 cduduct af 1 Parameters successfully set nTotBlocks successfully allocated Successfully changed directory to cdvyduct Working project directory C aerof lo test cduduct Number of global groups 1 read TESTCASE read SIMTYPE 2 read MACH 8 420088000808080888 read REYNOLDS 732677 00000000A read PR B 7200808080088080888 Global variables successfully read Press any key to continue Number of turbulence groups read TURBTYPE read DIRECIN H H read NUMTRIPS
72. Running the Project in the GUI 5 5 Simulation Results 5 6 Remarks 6 Introduction to AEROFLO Input Keywords 6 1 First Look at the Project File 6 2 Structure of the Project File 6 3 AEROFLO Input Keywords 6 4 Editing the Project File Directly 7 Running AEROFLO 7 1 Running the Program in Command Line 7 2 Restarting from a Previous Calculation 7 3 Example of Modifying and Restarting a Calculation 8 Prepare AEROFLO Mesh File 8 1 General Requirements 8 2 Grid Formats 8 3 Right Hand Rule 9 AEROFLO Output 91 Result Files 9 2 Log Output 10 Specifying Initial Conditions 10 1 Default Initial Conditions 10 2 Global Initial Conditions in the Project File 10 3 Initial Condition Input Files 10 4 Setting the Initial Conditions in Block Data Files 11 Specifying Boundary Conditions 11 1 Boundary Precedence Rules 11 2 AEROFLO Boundary Condition Types 43 49 50 50 51 51 56 56 57 60 60 62 63 70 70 70 74 76 76 78 79 79 79 80 82 83 83 84 12 Turbulence Models 12 1 Introduction of Turbulence Modeling 12 2 Reynolds Averaged Navier Stokes RANS 12 3 Large Eddy Simulation LES 12 4 Direct Numerical Simulation DNS 12 5 Hybrid Models 12 6 Selecting Turbulence Models 13 Numerical Schemes 13 1 Introduction of Numerical Schemes 13 2 Spatial Differencing Schemes 13 3 Time Integration Schemes 13 4 Selecting Numerical Schemes 14 Parallel Computation in AEROFLO 14 1 Running in Parallel 14
73. SNORMAL 1 the second nodal point from the boundary surface is assumed to form a normal with the adjacent boundary node If the boundary nodes are not normal interpolation is necessary to compute the values when the Neumann and flux conditions are applied at the boundary This results in a faster scheme Because boundary conditions are applied at every sub iteration it is important to designate normal surfaces to speed up the calculations This variable takes on a value of 0 or 1 The default value is ISNORMAL 1 IBCS IBCE The start and end nodal points in i for a boundary lying in the i j k i planes The default values are 1 and IE respectively JBCS JBCE The start and end nodal points in j for a boundary lying in the i j or j k planes The default values 1 and JE respectively 136 KBCS KBCE The start and end nodal points k for a boundary lying in the j k or k i planes The default values are 1 and KE respectively CNORM For characteristic inflow or outflow boundary conditions CNORM is used to provide the coefficient for the unit normal in the direction of the inflow OBLOCK For coupled conditions this keyword specifies the block to which the current block is coupled OSIDE For coupled conditions this keyword specifies the side of the other block to which the current block is coupled VARI For boundary conditions specified in simple equation form eg rho VARI refers to the second
74. Therefore the Compact scheme is only suitable for incompressible and subsonic flows The 6 order compact scheme is normally used in house at TTC Viscous Fluxes The viscous flux terms which are the viscous shear stress and heat flux terms have an elliptic character Those flux components can be computed with the central difference method In AEROFLO the viscous fluxes are discretized with explicit second order central differences when the MUSCL scheme is used for the convective fluxes and with high order central differences when the Compact sixth order or WENO fifth order schemes are used for the convective fluxes For diagnostic and research purposes the current version of AEROFLO enables the selection of the metric differencing scheme In general the selected metric and spatial schemes should be the same 96 13 3 Time Integration Schemes In AEROFLO the following time integration schemes are used Runge Kutta Scheme The classical fourth order explicit Runge Kutta scheme is used in its low storage form Because of its relatively severe stability constraint small CFL number is needed the computational cost of RK4 is high JBeam Warming Scheme The implicit second order Beam Warming scheme is also supported in AEROFLO The approximate factorization procedure is used to enhance scheme stability and make the computations go faster Pulliam s simplified diagonalized method is used to reduce the
75. University Press 2000 Roe P L Characteristic Based Schemes for the Euler Equations Annual Review of Fluid Mechanics Vol 18 1986 pp 337 365 Shih T H and Liu N S Partially Resolved Numerical Simulation from RANS towards LES for Engine Turbulent Flows AIAA 2004 0160 Shu C W Essentially Non Oscillatory and Weighted Essentially Non Oscillatory Schemes for Hyperbolic Conservation Laws ICASE Report No 97 65 November 1997 Smagorinsky J General Circulation Experiments with the Primitive Equations I The Basic Equations Mon Weather Rev 91 1963 pp 99 164 Spalart P R and Allmaras S R A One Equation Turbulence Model for Aerodynamic Flows La Rech A erospatiale V 1 1994 pp 5 21 Spalart P R Jou W H Strelets M and Allmaras S R Comments on the Feasibility of LES for Wings and on a Hybrid RANS LES Approach In Advance in DNS LES C Liu and Z Liu Eds Greyden Press Columbus Ohio 1997 van Leer B Towards the Ultimate Conservative Difference Scheme V A Second Order Sequential to Godunov s Method Journal of Computational Physics Vol 32 1979 pp 101 136 Wilcox D C Turbulence Modeling for CFD pu Edition DCW Industries 1998 157
76. ables Flow Parameters Specify As Non Dim Dimensional Conductivity o 263000 01 Density 116140E 01 Length Scale 0 2 Pressure 2 000000 02 Specific Heat 0 100700E 04 Temperature 200 0 00 Velocity 20 000000 00 Viscosity 0 184600E 04 Figure 4 6 The Input of Dimensional Global Flow Parameters Manage Grid Blocks button This button opens up the Manage Grid Blocks dialog box which is used to specify the structured grid blocks that are contained in a project and the boundary conditions for the blocks Figure 4 7 is a screen shot of the Manage Grid Blocks dialog box The Add New Block button opens up a new dialog box that allows you import a grid block to the project The Modify Selected Block and Delete Selected Block buttons allow you to modify and delete a grid block that is selected in the Selected Block drop down menu The Add Boundary Conditions button opens up a new dialog box that allows you add new boundary conditions for a block at a selected block boundary that is selected in the BC on Blocks drop down menu The Modify Selected BC and Delete Selected BC buttons allow you to modify and delete a boundary condition that is selected in the Selected BC dialog box The Display Block button allows you to turn the display of the selected dialog box on or off The Overset Setup button opens the Overset Setup dialog box and allows you to set the overset boundary condition 27 Manage Blocks
77. aning of the primary keywords In the next section we will analyze this file in detail 51 cdvduct afl MA MM A M M CE Project File Name SGLOBAL TITLE Converging Diverging DUCb g ee eeneoee ettet re pne Project Title FOLDER lt EE Project Subfolder Directory SIMTYPE ESSEC ERTS TTS Simulation Type 2 CFD MACH REYNOLDS 732677 0 PR 045000080 et ged dE Mach Number S Reynold Number 0 7200000 e Prandtl Number ORDER 2 5 BCSTYLE 2 SEND SOVERSET SEND STURB TURBT TUVALUE 0 1000000 Pd RESET SEND YPE KE LL S uM EE Turbulence Model 7 Abid Turbulence Intensity for k e model EE Set the initial k e values SSPATIAL Spatial Scheme SCHEME 55 5 e E a 5 MUSCL METRI VISCO C NEE Metric Scheme 0 214 order central US 1 3 ly 1 gp 2 Viscous 1 true VISCHEME 0 VISCMON CUTOF ISOTROPI ICUT CUTOF 1 5 0000001E 02 0 0 0 0 FI 5 0000001E 02 FI Il ISOTROPJ 0 JCUT SUTHE SEND 0 0 0 RIN 0 3800000 STIMESTEP SCHEME lt BW2 EE Time Scheme BW2 Beam Warming MAXIT ER 10000 Maximum Number of Iteration Steps GLOBALDT NEE e eeh Iteration Time Step Size SUBDT GLOBT SUBTO SEND 9 9999998 03 OL 1 0000000E 30 L 1 0000000E 03 SDAMPING TYPE 3
78. ation Scheme dialog box which allows you to specify the time integration scheme Figure 4 12 is a screen shot of this dialog box The Time Scheme drop down menu allows the user to specify the time integration scheme The currently supported options in AEROFLO include e Beam Warming scheme e Beam Warming scheme with approximate diagonalization scheme e Runge Kutta scheme The Use fixed time steps button causes fixed time steps to be used for time advancement When it is not selected variable time steps are used The value of the time steps is calculated based on the flow conditions and the CFL number The Use preconditioner button causes preconditioner formulation to be used with the time advancement scheme This allows stable calculations of low speed flow Ma lt lt 0 1 with larger time steps than when this option is not selected The Max No of Time Steps input box is used to specify the maximum number of time steps for the simulation The Time Step Size input box is used to specify the time step size When variable time steps are used this input is used only for the initial time step size The Tolerance input box is used to specify the value of the residual at which the simulations are considered to have converged Sub iterations may be used for the Beam Warming scheme This allows bigger time step sizes to be used The Max No of Sub Iterations input box is used to specify the number of sub iterations to use per time step The Sub Iteration
79. both blocks would be as follows FACEBC BLOCK BLOCK1 SIDE 5 TYPE 2 IBCS 4 OBLOCK BLOCK2 OSIDE 6 IOBCS 1 END FACEBC BLOCK BLOCK2 SIDE 6 TYPE 2 IBCS 1 OBLOCK BLOCK1 OSIDE 5 IOBCS 4 END The result of the above command is shown in Figure 15 2 b Note that the end points of the coupling match 109 are not indicated As with all boundary conditions using the FACEBC command when not specified the start point defaults to the start of the grid block including any ghost nodes and the end point defaults to the end of the grid block including any ghost nodes The commands below yield the same results as those presented in Figure 15 2 a FACEBC BLOCK BLOCK1 SIDE 5 TYPE 2 IBCS 4 IBCE 8 OBLOCK BLOCK2 OSIDE 6 IOBCS 1 IOBCE 5 END FACEBC BLOCK BLOCK2 SIDE 6 TYPE 2 IBCS 1 IBCE 5 OBLOCK BLOCK1 OSIDE 5 IOBCS 4 IOBCE 8 END However the second set of commands is preferred to the former as it helps to avoid incorrect specification of boundary conditions with its loose specifications This is illustrated with an example in the next section 15 1 3 When to Indicate or Omit Coupling Limits Consider the five block example in Figure 15 3 110 b Figure15 3 2D Example of Automatic Partial Co
80. can perform administrative functions including loading an existing project saving the project you are working on and initializing all data fields to start a new session Figure 4 3 is a screen shot of the Load Save Project dialog box New Project Load Project Save Project As Loaded File tempread cfd Project Title Project Subfolder Figure 4 3 Load Save Project Dialog Box In the Load Save Project dialog box the New Project button causes all input to be cleared and default values restored The Load Project button opens up the file navigation dialog box to enable you load a previously saved project file The Save Project button causes all project variables and parameters to be saved to the currently opened project file The Save Project As button opens up the file navigation dialog box to enable you save a project to a different file and folder The Loaded File text box gives the name of the currently open project file The Project Title input box allows you to specify a project title for administrative purposes The Project Subfolder input box allows you to specify a project subfolder of the current folder where the grid and initial conditions file may be located This is good for project organization 23 Problem Setup button This button opens the Problem Setup dialog box where you specify the inputs that are required for a simulation The Problem Setup Dialog Box will be described in Section 4 3 Graphics Disp
81. condition that you wish to modify in the Selected BC list and click Modify Selected BC to modify it You can also use Delete Selected BC to delete the wrong boundary condition and create a new boundary condition to replace it When you finish setting all boundary conditions click Close to close the Manage Blocks dialog box and return to the main graphical interface Set Initial Conditions There are four initial conditions need to be specified which are listed in Table 5 1 Use the following steps to set each of the initial conditions a Click the Initial Conditions button to open the Initial Conditions dialog box b To specify the u initial condition Click the Add New Initial Conditions button to open the New Initial Condition dialog box In the Variable drop down menu select u velocity In the Value input box type 1 0 Click OK to close the New Initial Condition dialog box specify the v 0 initial condition Click the Add New Initial Conditions button to open the New Initial Condition dialog box In the Variable drop down menu select v velocity In the Value input box type 0 Click to close the New Initial Condition dialog box 47 To specify the p initial condition Click the Add New Initial Conditions button to open the New Initial Condition dialog box Inthe Variable drop down menu select Density Inthe Value input box type 1
82. d Timestep variables successfully read Damping filtering variables successfully read Movie variables successfully read Debug variables successfully read No of blocks read 1 No of block donors read The style in convertbcstyle is No of face bcs read Initial conditions read and applied 1 Spatial differencing variables successfully read End of the input file 0 Output files folder D alabi Research aeroflo cdyduct reading block grid data double precision from mesh 001 PLOT3D Number of blocks in file 1 read 81 51 1 expecting 81 51 Figure 4 19 Graphics Display Dialog Box in Text Mode 4 5 Graphics Controls Dialog Box This dialog box controls the display in the Graphics Display dialog box Figure 4 20 is a screen shot of the dialog box The control functions are controlled by the following buttons Restore Returns the graphics display to its original state after a series of transformations e g zoom Grid Toggles the display of a grid to help with graphic positioning while using the mouse in the graphics area Limit Determines the physical limit of the display environment in x y z Note that the limits are also automatically set when blocks are loaded such that the blocks are contained optimally within the display area 40 Zoom Performs a visual zoom of the display area on a user selected part of the display The user selects a zoom box via a mouse click of the top left and bottom r
83. d to follow the following steps 1 Launch AEROFLOGUI You can double click the multidisc exe in AEROFLO s installation directory or find the Programs gt AEROFLO gt AEROFLOGUF in the Start menu 2 Select Simulation Type Make sure the selection of the simulation type is CFD this is the default selection 3 Create a New Project File a Click the Load Save Project button b Click the New Project button c Inthe Project Title input box type Converging Diverging Duct This is only for administrative purposes you may change it to any other words 43 4 Save the Project File Click the Save Project As button A file navigation dialog box is opened Change the directory to the folder where you want to save the project file Here we assume the file is saved in folder c aeroflo test If the folder does not exist you must create it first In the File name input box type in the name of the project file Here we assume the name of the file is cdvduct afl The file extension a is suggested file extension for AEROFLO project files You can also use other extensions that have the native plain text format such as Click Save to save the file A notice will automatically pop up showing the message Project Saved in cdvduct afl Click OK to continue 5 Specify the Subfolder a In the Project Subfolder input box type in the name of th
84. dialog box To add the P 3 37564 boundary condition V NW WV Click the Add Boundary Condition button to open the Add New BC dialog box In the Type drop down menu select Dirichlett In the Variable drop down menu select Pressure In the Value input box type 3 37564 Click OK to close the Add New BC dialog box Outlet 1 81 face Select Last I Face in the BC on Blocks drop down menu By clicking Refresh in the Graphic Controls dialog box the outlet boundary face is highlighted white colored in the Graphics Display dialog box To add Ou Ox 0 boundary condition Click the Add Boundary Condition button to open the Add New BC dialog box In the Type drop down menu select Neumann In the Variable drop down menu select u velocity Click OK to close the Add New BC dialog box To add Ov Ox 0 boundary condition Click the Add Boundary Condition button to open the Add New BC dialog box In the Type drop down menu select Neumann In the Variable drop down menu select v velocity Click OK to close the Add New BC dialog box To add 09 0x 0 boundary condition gt gt gt gt Click the Add Boundary Condition button to open the Add New BC dialog box In the Type drop down menu select Neumann In the Variable drop down menu select Density Click OK
85. e values ALPHAN ALPHAS ALPHA4 ALPHA3 ALPHA2 ALPHA These variables control the filter coefficients in all three directions at the interior fifth fourth third second and boundary nodes respectively Accepted values range from 0 4999 to 0 4999 A value of 0 4999 is the least dissipative ALPHAN 0 499 0 499 0 0 ALPHAS5 0 45 0 45 0 0 ALPHA4 0 45 0 45 0 0 ALPHA3 0 49 0 49 0 0 ALPHA2 0 499 0 499 0 0 ALPHA1 0 0 0 0 0 0 The above specification will use a filter coefficient of 0 499 at interior nodes of a simulation in the 7 directions and values of 0 45 0 45 0 49 0 499 and 0 0 at the fifth fourth third second nodal points from the boundary and boundary nodes respectively Please consult the appendix for notes and tables on acceptable values 128 16 6 OUTPUT Keywords The sub keywords in the OUTPUT keyword block specify the output and animation generation data Frequency of printing results A CGNS myres cgns and a TECPLOT file myres dat are generated at each PRINTFRQ iteration FORMAT Specifies the preferred output format The default value is TECPLOT Note that the CGNS result output restart file myres cgns is always generated regardless of the value of the format CGNS TECPLOT PLOT3D TECANIM myres cgns result output restart file is generated Intermittent result files are generated with names res1 cgns if T
86. e following BLOCK SIDE TYPE Characteristic Inflow Outflow Type 41 42 The incoming and outgoing Riemann invariants are then 2 q n y 1 2 unt 23 y 1 From that we have q n R R 86 y 1 R R 4 2 At the outflow boundary n q q n S S At the inflow boundary 4 4 n q q n 8 5 o The density and pressure can be calculated from c and s which are 5 mf 2 p II Sea diS Note that this boundary condition acts on existing values of u v w r and P Consequently it must be applied after either inflow or other Dirichlett conditions have set the appropriate values for those variables Specifying this boundary condition requires the following BLOCK SIDE TYPE CNORM List of Boundary Condition Types BC No Solid Wall 2 Coupling 3 Overset boundary condition 8 Coupling due to periodicity 9 C Grid 10 Dirichlett Symmetry 13 Symmetry in any plane 14 Symmetry in j any plane 15 Symmetry in k any plane 23 Neumann 0 flux 24 Specified flux 87 30 Inflow 31 Outflow 32 Free stream 41 Characteristic Inflow B C 42 Characteristic Outflow B C 52 Initial value 59 Singular point surface e g sphere grid 60 i axes axisymmetric around I at specified face 61 j axes 62 k axes 71 S
87. e on the same side as the trip points TUVALUE The turbulence intensity for x e and model RESET Determine if the turbulence intensity set in TUVALUE is used to initial the turbulence calculation 119 16 3 SPATIAL Keywords The sub keywords in the SPATIAL keyword block determine the spatial difference data This keyword block is required SCHEME Spatial differencing scheme Specified for all three directions on the same line e g SCHEME 5 5 5 specifies MUSCL scheme in all three directions A WN e 33 999 METRIC Original second order central scheme First order Roe Fully upwind second order Roe using MUSCL with k 1 Second order Roe scheme with Fromm reconstruction 0 Third order upwind biased Roe scheme k 1 3 Second order subset of the Roe MUSCL scheme k 1 Compact scheme WENO scheme No solution Metric differencing scheme 12 13 VISCOUS 274 central differencing Compact scheme Same scheme used for inviscid and viscous fluxes Compact scheme WENO Viscous specification in all three directions Specified on the same line e g VISCOUS 1 1 1 implies that viscous calculations will be assumed in all three directions 120 VISCHEME Scheme used to compute the viscous terms 0 Central order formulation for computing the viscous terms 1 Compact difference formulation for computing the viscous terms VISCMON Determines if the cros
88. e project subfolder Here we assume the name of the subfolder is cdvduct The subfolder is the place where the project file can find the grid and initial files and where AEROFLO outputs the results for the project Properly setting the subfolder can make the project much more organized Create the cdvduct folder in the directory c aeroflo test in your operating system If the subfolder does not exist when you save the project an error message will be shown Click the Save Project button A message is popped up to notice the saving of the file is successful Click OK to continue Click OK to close the Load Save Project dialog box and return to the main graphical interface of AEROFLO 6 Set Global Flow Conditions Click the Problem Setup button This will open the Problem Setup dialog box if it is closed Click the Global Flow Conditions button The Global Flow Variables dialog box is opened Make sure that the Non Dim button is selected as this particular problem is nondimensional Input 0 46 and 732676 8 for the Mach No input box and Reynolds No input box respectively Leave the Prandtl No as the default value 0 72 as it is not important for the current problem Click OK to close the Global Flow Variables dialog box You can find the Global Flow Conditions button is disabled grayed This indicates that it has been processed This happens for every button in the Problem Setup dialog box
89. ect You 33 should access this feature if you intend to perform simulations with different spatial schemes in different blocks The Delete Specification button deletes the current spatial scheme specification The Block drop down menu allows you to select the block to which the current specification applies The Simulation Type radio button allows you to specify viscous or inviscid calculations for the block in the current specification The Sutherland Law button is used to apply the Sutherland law for viscosity Provide the value of the Sutherland law coefficient in the accompanying input box The Metrics dialog box selects the scheme for calculating the metrics of the coordinate transformation The Configure button opens a dialog box for the specification of the parameters of the selected spatial scheme The Viscous Calculations button allows you to specify the numerical procedure used in computing the viscous terms Scheme specification Specification 1 New Specification Delete Specification Block All blocks Simulation Type VISCOUS Inviscid Use Sutherland Law Coefficient 0 3800000 J Metrics Roe Scheme 3 Roe Scheme 3 None Compact Roe Scheme 4 Roe Scheme 4 Compact Conser Configure Configure Isotropic Fix Off Isotropic Fix Off Viscous Calculations 9 Compact Central Differencing Figure 4 13 Spatial Differencing Scheme Dialog Box Spatial Damping Filtering button This button opens a Spatial Damping Filterin
90. ed by commas e g POINT COORDS 0 1 0 0 0 5 END 143 16 14 BOX Keywords This keyword block is used to define a box in space for the blanking of regions POINTS List of points defining the eight corners of a 3D box in space BLOCKS List of blocks whose sections may be blocked where they lie within the box defined by poles Example BOX POINTS 1 2 3 4 5 6 7 8 BLOCKS BLOCK1 BLOCK2 END 144 FAQ 1 My computation gives me the error message STOPPING IN SUBROUTINE CXMU DUE TO NEGATIVE TEMPERATURE and then stops running ANS This is because the time step size is too large Try to use a smaller time step size 2 My computation gives me the error message SOLUTION INTEGRITY IS IMPAIRED and then stops running ANS This is also because the time step size is too large Try to use a smaller time step size 3 My computation gives me the error message NEGATIVE JACOBIAN in the beginning of the calculation ANS This is because the block grids violate the right hand rule Try to modify the grid file to solve the problem 145 Summary of AEROFLO Keywords AEROFLO input files expect three types of data Character strings Character string arrays nteger nteger arrays Real Real arrays Logical or Ei GLOBAL VARIABLES GLOBAL Keyword Data Type Default Value Range Required TITLE
91. ent platforms Windows Linux 2 1 Windows System Requirements The installation of the AEROFLO in Windows requires the following Windows 2000 XP 2003 Intel R Pentium R or equivalent processor 128MB of RAM Installation File mpiaeroflo_06_06 zip The installation file mpiaeroflo_xx_xx zip can be found in the product CD or can be downloaded from the TTC Technologies website http www ttctech com in the filename represents the version information For example mpiaeroflo_06_06 zip represents the June 2006 version of AEROFLO mpich nt 1 2 5 exe Besides the AEROFLO installation file you may also need the MPICH for the parallel calculation MPICH developed by Argonne National Laboratory is a free portable implementation of MPI a standard for message passing protocol for distributed memory applications used in parallel computing MPICH can be downloaded from http www mcs anl gov mpi impich Another MPI implementation package MPIPRO is also supported by AEROFLO However MPICH is assumed to be used in this manual Installation Steps 1 To install AEROFLO in Windows you must first install MPICH To install MPICH you can use the following steps If your system already has MPICH installed skip Step 1 e Double click the installation file WinZip Self Extractor mpich nt 1 2 5 exe Unzip and start the setup utility to install MPICH on this g machine You will be ab
92. es of high order schemes for subsonic transonic and supersonic flows AIAA 2006 0299 The 44th AIAA Aerospace Sciences Meeting and Exhibit 9 12 January 2006 Reno Nevada Alabi K Safta C and Ladeinde F 2005 High order hole cut procedure for realistic geometries at all speeds The 44th AIAA Aerospace Sciences Meeting and Exhibit 9 12 January 2006 Reno Nevada Cai X Ladeinde F and Alabi K 2006 High fidelity Aeroelastic Computations for Realistic Aerospace Systems Paper Submitted to The 44th AIAA Aerospace Sciences Meeting and Exhibit 9 12 January 2006 Reno Nevada Cai X D amp Ladeinde F 2005 Comparative Studies of Two POD Methods for Airfoil Design Optimization 3rd MIT Conference on CFD CSM Cambridge Massachusetts Alabi K amp Ladeinde F 2005 Treatment of Blank Nodes in a High Order Overset Procedure AIAA 2005 1269 43rd AIAA Aerospace Sciences Meeting and Exhibit 10 13 January 2005 Reno Nevada Cai X D amp Ladeinde F 2004 A Comparison of Two POD Methods for Airfoil Design Optimization 2005 4912 4th AIAA Theoretical Fluid Mechanics Meeting 9 12 January 2006 Reno NV Alabi K amp Ladeinde F 2004 Parallel High Order Overset Grid Implementation for Supersonic Flows AIAA Paper 2004 0437 42nd AIAA Aerospace Sciences and Exhibit Reno NV 5 8 January 2004 Cai X amp Ladeinde F 2004 High Order Formulation for a Hybrid ROM method for linear aeroelasticity AIAA Paper 2004
93. ess than the maximum grid dimension are solved using the RANS model while regions where the turbulent length scale exceeds the grid dimension are solved using the LES model The DES simulations in AEROFLO are based on the 92 Spalart Allmaras model Partially Resolved Numerical Simulation Abid The Partially Resolved Numerical Simulation PRNS procedures are designed to provide a unified simulation strategy from RANS to LES for high Reynolds number complex turbulent flows The governing equations for the PRNS method are the temporally filtered Navier Stokes equations in which the dependent variables can be construed as either the statistical mean as in RANS the partially resolved large scale as in LES or the instantaneous as in DNS values of turbulence while the effects of unresolved scales are modeled based on the size of the temporal filtering In AEROFLO unresolved stresses for near wall flows are calculated using Abid s model This method is still under development 12 6 Selecting Turbulence Models AEROFLO incorporates the following turbulence models M Reynolds Averaged Navier Stokes model RANS Spalart Allmaras model Abid s model Launder Sharma model Menter s SST k w model High Reynolds number model arge Eddy simulation model LES Smagorinsky model Dynamic model Direct Numerical Simulation model DNS Hybrid model Detached Eddy Simulation DES based
94. flow Weighted essentially non oscillatory WENO scheme 5 for high speed flow Standard low order spatial schemes MUSCL Monotone Upstream centered Schemes for Conservation Laws scheme 2 9 First order Roe scheme Second order central schemes Several time integration schemes High order Runge Kutta procedures 4 order Implicit Beam Warming schemes 2 9 Beam Warming with preconditioning formulation very low speed flow AEROFLO also uses the parallel computation technique to calculate very complicated large and realistic problems Multi block technique Overset chimera technique Automatic domain decomposition Automatic detection of interior sub domain interface Aeroelasticity Calculation High order multi block flow solver Platform for non linear aeroelasticity full blown flow equations can be used Mode based structure solver Dynamic mesh procedure for adaptive structures Dynamic flow structure coupling Linear ROM method P K method Basic CFD Calculation Navier Stokes solver inviscid viscous laminar turbulent Various turbulence model DNS RANS LES All speed regimes subsonic transonic supersonic and hypersonic High order calculations Standard low order procedure is also available Accurate moving body calculations Multi platform parallel calculations Easy to use interface Aeoracou
95. g dialog box which is used to specify damping and filtering schemes Figure 4 14 is a screen shot of the dialog box The Damping Filtering buttons are used to select the damping and filtering options The information required in the remainder of the dialog box depends on the option selected here If the Filtering option is selected as shown in Figure 4 14 the following information is required 34 Filtering On Off Filtering can be turned on and off selectively in any of the i j k coordinate directions Frequency Specify the number of filtering operations to be performed per time step in this input box Configure This button opens up dialog boxes for the specification of the details of the filtering procedure Ifthe Damping option is selected as shown in Figure 4 15 the following information is required Boundary Layer Damping This specifies the number of nodes from the boundary below which damping is not applied The default value is 1 which implies that damping is applied at all points Damping Coefficients These are the coefficients for the fourth and second order terms of the damping function respectively Implicit Damping Coefficients These are the coefficients for the fourth and second order terms of the implicit damping function respectively Implicit Damping Modifiers The first term is a relaxation parameter for the implicit damping function while the second adds a small source term to the dam
96. he grid in I direction JSIZE Size of the grid in J direction KSIZE Size of the grid in K direction FACEBC Pressure boundary condition data BLOCK Name of the block to which the boundary condition refers SIDE Side of the block 1 first I face 1 last I face 2 first J face 2 last J face TYPE Boundary condition type 1 solid wall 10 Dirichlett 23 Neumann VARIABLE Variable which the boundary condition refers 1 2 3 v 4 w 5 P VALUE Values assigned in the boundary condition SINITIAL Initial boundary condition data VARIABLE Variable which the initial condition refers 1 2 u 3 4 5 VALUE Values assigned to the variable in the initial condition Table 6 1 The Primary Keywords Used in Project File cdvduct afl 59 7 Running AEROFLO In this chapter we will introduce how to run an AEROFLO project in command line and how to restart a calculation from a previous one 7 1 Running the Program in Command Line We have introduced how to run an AEROFLO problem in the GUI in Chapter 5 However an AEROFLO project can also be run in command line instead of in the GUI In fact the calculation speed is faster when running in command line However before you start to run the program in command line make sure the following requirements are satisfied grid files must be put in the project sub folder or its path information must be included in the
97. he group applies 123 16 4 TIMESTEP Keywords The sub keywords in the keyword block specify the time differencing data This keyword block is required MAXITER This variable represents the maximum number of iterations for which to run the problem SCHEME The time integration schemes supported in the current version of AEROFLO include BW2 Beam Warming approximate factorization with diagnolization simplification BW1 Beam Warming approximate factorization RK4 Fourth Order Runge Kutta an explicit scheme DIAGONAL This variable takes on values of 0 or 1 and determines if diagonal formulation will be used for the Beam Warming computations When a value of 1 is used diagonal formulation is used and results in slightly faster time integration SUBON Determines if sub iterations will be performed This option is only activated for the Beam Warming schemes MAXSUB Determines the maximum number of sub iterations if convergence is not reached first during the sub iteration stages The convergence criteria for sub iterations are controlled by SUBTOL see below GLOBALDT The time step size for iterations It is recommended that a value smaller than 1 2 MIN Ax Ay Az be used Ax Ay Az represent mesh spacing at cells in the mesh For calculations using preconditioners GLOBALDT can usually be set to a very large value SUBDT Step size for sub iterations It is recommended that a value smaller than
98. here is a continuity of mesh across the interblock region Note that these blocks may have simply been the result of a block subdivision from one huge grid To perform calculations on blocks with coincident node overlap the user only needs to indicate the overlap boundaries or faces for each block No information on topology is necessary AEROFLO will perform a search of all blocks to determine the appropriate blocks to provide values for each overlapping boundary To speed up the calculations the user may indicate possible donors using the BLOCK DONORS keyword In addition the user may indicate that the type of overset is a coincident node using the keyword OVERSET TYPE 1 In such a situation AEROFLO simply supplies the value from the matching donor node rather than interpolating for values for the overset node from the donor block 15 1 1 Coupling Grid Blocks When two grid blocks touch but do not overlap AEROFLO can create an overlap between the two blocks 107 This sub section discusses the automatic generation of an overlap between two blocks that have compatible coincident nodes at the boundaries at which they touch To specify coincident node overlap or coupling of two blocks use the TYPE 2 boundary condition with the FACEBC command Consider the simple example in Figure 15 1 a Ghost nodes of Block 2 coupled to Block 1 4 ESTEE of Block 1 coupled to Block 2 nodes L
99. ids Abutting touching grids can be extruded in two ways a When a coupling TYPE 2 boundary specification is used to connect both grids but the grids do not have coincident nodes at the interface and b By using TYPE 85 of the FACEBC command An example of grids extruded due to an incompatibility between abutting grids is shown in Figure 15 4 Note that the grids are extruded at a normal and with similar grid size as the preceding grid cell Original grid Block 2 interface j i a L b 1 Figure 15 4 2D Example of Overset Blocks from Abutting Grids with Incompatible Nodes at the Abutting interface a Original blocks supplied by the user b Blocks showing the ghost nodes following the automatic overlap 15 3 Mixed Block Calculations To perform calculations involving coincident node overlap across some blocks and non coincident node overlap across other blocks the user may set up the problems in the same way as those for non coincident 112 node overlap However using the keyword OVERSET COINNODE 1 AEROFLO will first search for an exact node donor for an overset node before searching for an interpolating donor 15 4 Specifying Blank Regions Three methods have been provided specifying blank regions in AEROFLO 1 Direct specification using grid points Blank regions are specified this way us
100. ight of the region to be zoomed into Refresh Redraws the graphics display area Graphics On Off Toggles the graphics area between text and graphics modes In graphics mode the blocks are graphically displayed while in text mode messages and diagnostics are reported EEN Status Bar Figure 4 20 Graphics Controls Dialog Box 4 6 Using the GUI Help AEROFLO includes an integrated HTML based online help system that provides easy access to the program documents In each dialog box there is a blue Help button on the top left corner By clicking the Help button an HTML webpage that contains the help information for the dialog box will be automatically opened 41 5 Tutorial Using the AEROFLO GUI to Simulate Flow Through a Converging Diverging Duct In this chapter the detailed procedures for simulating a flow through a converging diverging duct are introduced After following this tutorial you will be familiar with the AEROFLO GUI and how to set up an AEROFLO project and run the project by using the AEROFLO GUI 5 1 Problem Description The selected sample problem is a flow through a converging diverging duct The physical domain has dimensions as shown in Figure 5 1 where ba 0 14435 ft is used as the dimensional length scale This provides a Mach number of 0 46 at the inlet and a Reynolds number of 732 676 8 The nondimensional inlet and outlet pressures are 3 375640 and 3 263250 respectively 14 hy
101. ile button opens up a file navigation dialog box to enable you to load an initial condition file The I C File text box shows the name of the initial condition file that 1s currently loaded Add New Block Block Name BLOCK2 Mesh Format PLOT3D No of nodes to place at overlaps Topology Mesh File Load Block Transform Block Add Initial Conditions File Figure 4 8 Add Modify Block Dialog Box Figure 4 9 is a screen shot of the Add New BC Modify BC dialog box This dialog box opens when you click the Add Boundary Condition or Modify Selected BC buttons This dialog box is used to add or modify selected boundary conditions of a grid block The first selection in this dialog box is the boundary conditions type All other inputs in this dialog box depend on the type of boundary condition selected The Type drop down menu is used to select the type of boundary condition AEROFLO supports the following types 29 Block coupling C Grid Dirichlett Flux specified value Neumann Overset boundary Periodicity coupling Slip wall Solid wall Specified equation Subsonic freestream Subsonic inflow Subsonic outflow Symmetry Detailed information about these boundary conditions will be given in Chapter 11 Add New BC Type Coupled to another block Coupled to block meshO Face on block 1 Range in J 0 to 0 to Range in K Range on Other Block Range in J 0
102. in AEROFLO AEROFLO Aeroelasticity Manual describes how to perform aeroelasticity calculations in AEROFLO AEROFLO Electromagnetics Manual describes how to solve electromagnetic problem in AEROFLO Technical Support If you encounter difficulties while using AEROFLO please first refer to the corresponding User s Manual More resources about AEROFLO can be found on the AEROFLO website at http www ttctech com aero asp You can also contact TTC Technologies Inc to obtain further technical support iii Table of Contents Introduction 1 11 The Purpose of AEROFLO 1 2 AEROFLO Capabilities and Features 1 3 Program Structure 1 4 The Structure of this Manual Installation 2 Windows 2 2 Linux Unix Basic Procedures for CFD Analysis Using AEROFLO 3 1 Detailed Procedures 3 2 Creating Grids 3 3 Setting Up an AEROFLO Project 3 4 Running an AEROFLO Project 3 5 Plotting Results 3 6 Revision and Recalculation AEROFLO s Graphical User Interface GUI 4 1 GUI Components 4 2 Main Program Dialog Box 4 3 Program Setup Dialog Box 4 4 Graphics Display Dialog Box 4 5 Graphics Controls Dialog Box 4 6 Using the GUI Help Tutorial Using the AEROFLO GUI to Simulate Flow Through a Converging Diverging Duct 5 1 Problem Description 5 2 Getting the Computational Grid iv 14 16 16 18 18 19 19 19 21 21 22 25 38 40 41 42 42 43 5 3 Setting Up the Project File Using the AEROFLO GUI 5 4
103. incident Node Overlapping of Three Blocks a Original blocks supplied by the user b Blocks showing the ghost nodes following the automatic coupling FACEBC BLOCK BLOCK1 SIDE 5 TYPE 1 END In Figure 15 3 a specifying a loose wall boundary condition as shown above on the j face of Block 3 will result in the application of wall conditions on all of the nodes at the j 1 face including any ghost nodes This includes the original 8 nodes of Block 3 as well as the additional 2 ghost nodes coupled with Block 1 This is due to the precedence of the wall boundary condition over the overset boundary condition The correct boundary condition is shown below FACEBC BLOCK BLOCK1 SIDE 5 TYPE 1 IBCS 1 IBCE 8 END Similarly specifying a loose match between Blocks 1 and 2 results in an incompatibility and the blocks are extruded rather than coupled which is usually not a major problem as high order interpolation is used to exchange results between the grids 15 2 Overset Multi Block Calculations with Non Coincident Node Overlap AEROFLO also performs overset calculations involving multi blocks with non coincident node overlap 111 across the interblock regions To perform these calculations the user does not need to provide any special input However to speed up the calculations the user may indicate possible donors using the BLOCK DONORS keyword 15 2 1 Extruding Incompatible Gr
104. ing the FACEBL keyword and TYPE 95 The region to be blanked is further qualified by the IBCS IBCE JBCS JBCE KBCS and KBCE keywords For example the specification below causes the grid points 1 1 5 j 10 25 k 1 End to be blanked FACEBL TYPE 95 IBCE 5 JBCS 10 JBCE 25 END 2 Direct specification using a geometric box The geometric box is specified with the box keyword The box is further defined by the POINT keywords POINT COORDS 0 0 0 0 0 0 END POINT COORDS 0 0 1 0 0 0 END BOX POINTS 1 2 3 4 5 6 7 8 BLOCKS BLOCK END The example above causes sections of BLOCK with name BLOCKT that lie within the box specified the corner points above to be blanked 3 Automatic cuts based on block overlaps These types of cuts may be specified using the MESHCUT keyword The procedure equates the 113 specification of a primary block or cutter One or more blocks whose grids will be blanked in the regions in which they overlap the primary block are then specified To further qualify these types of cuts the order and periodicity of the cut may be specified The order refers to how many overset nodes will be placed at the fringe of the cut as well as how many nodes will be located at the offset between both blocks Periodicity takes on the following values PERIODICITY i j 0 Places an overlap at the boundary of the cut on both ends 1 233 Ex
105. is used to specify the single mesh block used in this problem The data includes the format grid sizes and topology information for the mesh block Ten FACEBC blocks are used to specify ten boundary conditions and four INITIAL blocks are used to specify four initial conditions The meaning of each block is also noted in Figure 6 1 6 3 AEROFLO Input Keywords A detailed explanation of the primary keywords in this project file is given in Table 6 1 These keywords 56 correspond to the parameters chosen by the user in the GUI in the last chapter The other sub keywords are automatically generated by the GUI and are set to default values A complete reference of the AEROFLO keywords can be found in Chapter 16 6 4 Editing the Project File Directly After understanding the structure of the project file and the meaning of each of the AEROFLO keywords the user can directly write a new project file or edit an existing project file There are a few rules involved in creating an input file All group keywords must have a in front of them e g GLOBAL BLOCK keyword input groups must end with the SEND limiter All sub keywords must be followed by an equal sign followed by a value depending on the data type All sub keyword data entry lines must end with a comma Sub keyword values must be separated by a when more than one input value is required per sub keyword e g POINT 0 2 0 4 0 4
106. lation the results are nearly the same but require more calculation operations RESTART This keyword is used to generate or read overset information To remove the overhead of determining donors for overset nodes at the start of a restart calculation the overset information may be written to file by setting RESTART 2 On subsequent restarts RESTART 1 will read the overset information from restart files rather than recompute donors for overset nodes RESTART 0 is the default and causes the donor information to be computed every time but not written COINNODE In a mixed multi block calculation involving both coincident and non coincident node calculations the computation of donors for overset nodes can still be sped up for coincident overlap nodes by setting COINNODE 1 This causes AEROFLO to first search for an exact coincident node for an overset node COINNODE 0 is the default value PROJECT This determines if projection will be used at the interface of solid walls for overset boundaries PROJECT 0 is the default value and infers that projection will not be performed NUMITER While searching for donors for overset nodes AEROFLO may encounter nodes that have no donors De orphan nodes However AEROFLO may widen the allowance for declaring a node an orphan by allowing extrapolation from a close cell NUMITER controls this allowance The higher the value of NUMITER the higher the proximity of a node to a donor cell that is
107. lay button This button opens the Graphics Display dialog box which contains the visual display and output log The Graphics Display Dialog Box will be described in Section 4 4 Graphics Control button This button opens the Graphics Control dialog box which contains buttons to control the Graphics Display dialog box The Graphics Control Dialog Box will be described in Section 4 5 Solve button This button initiates the start of the simulation This assumes that all required input data for the task have been specified If this is not the case the computation may not be successful and the missing input will be indicated via a Warning Message Box Stop Pause button This button stops a simulation that has been initiated with the Solve button A simulation that is stopped or paused may be resumed with the Resume button Resume button This button resumes a simulation that has already started and was suspended via the Stop button View Results button This button opens up a dialog box where the output of a simulation can be viewed Exit button Press this button to close the program and end the current session 24 4 3 Program Setup Dialog Box The Problem Setup dialog box opens up other dialog boxes from which input is provided Figure 4 4 is a screen shot of the Problem Setup dialog box For a particular project you are only presented the dialog boxes that you will need for that project For instance the T
108. le to cancel later Cancel About e Click Setup Welcome to the MPICH Setup program This program will install MPICH on your computer lt is strongly recommended that you exit all Windows programs before running this Setup program Click Cancel to quit Setup and then close any programs you have running Click Next to continue with the Setup program WARNING This program is protected by copyright law and international treaties Unauthorized reproduction or distribution of this program or any portion of it may result in severe civil and criminal penalties and will be prosecuted to the maximum extent possible under law Next gt Cancel e Click Next Software License Agreement Please read the following License Agreement Press the PAGE DOWN key to see the rest of the agreement COPYRIGHT The following is a notice of limited availability of the code and disclaimer which must be included in the prologue of the code and in all source listings of the code Copyright Notice 1993 University of Chicago 1993 Mississippi State University Permission is hereby granted to use reproduce prepare derivative works and to redistribute to others This software was authored by Argonne National Laboratory Group Do you accept all the terms of the preceding License Agreement If you choose No Setup will close To install MPICH you must accept this agreement lt Back e Select where to
109. lip wall 80 Equation 90 User Defined Note The specifications of a boundary condition supersede the initial values at the boundary points which are specified in the initial conditions 88 12 Turbulence Models This chapter provides an elementary introduction to the turbulence models used in AEROFLO Different turbulence models will be introduced and compared with a few suggestions on the choice of an appropriate turbulence model 12 1 Introduction of Turbulence Modeling In turbulence the flow fields exhibit stochastic behaviors In this case an instantaneous flow variable or chemical species can be decomposed into a mean value time averaged ensemble averaged and a fluctuating value The fluctuating quantities are associated with the small scales of the flow If we want to directly resolve all the flow scales by solving the governing equations Navier Stokes we would need a very fine mesh This would cause the computation to be too expensive for realistic problems Furthermore the mean properties of the flow field are usually of interest in engineering applications Therefore the instantaneous governing equations are sometimes averaged to remove the small scales so that the averaged equations can be solved form the mean quantities This procedure which is referred to as the Reynolds averaged Navier Stokes RANS equations leads to governing equations that are less expensive to solve However because of the nonlinear nat
110. ll rho values AEROFLO File Format The AEROFLO data format is an unformatted binary file containing both the mesh and the solution variables As a result it can be used to provide the mesh data as well as the initial conditions data The format including both grid and solution data is shown below 12 If Turbulence flow with Sparlart Allmaras model IL JL KL ITERATION TIME lt lt RHO SP If Turbulence flow with k model IL JL KL ITERATION TIME X Y Z U V W P RHO k Else IL JL KL ITERATION TIME X Y Z U V W P RHO End if For MHD simulation the format is IL JL KL ITERATION TIME X Y Z U V W P RHO BFIELD IL JL KL integers representing the grid size in i j and k 73 ITERATION current iteration step 0 for a new problem TIME current time 0 0 for a new problem X Y Z three dimensional arrays exactly of size IL JL KL U V W P RHO three dimensional arrays exactly of size IL JL KL for the u velocity v velocity w velocity pressure and density variables SP k three dimensional arrays exactly of size IL JL KL for the Spalart Allmaras variable and for k e turbulence models respectively BFIELD four dimensional arrays exactly of size IL JL KL 3 for the MHD B field variables A FORTRAN 90 segment for writing a grid in the AEROFLO format for a CFD Navier Stokes calculation is shown below REAL DIME
111. lowing Roe schemes First order Roe Fully upwind second order Roe Second order Roe scheme with Fromm reconstruction 95 Third order upwind biased Roe scheme MUSCL Scheme The MUSCL Monotone Upstream centered Schemes for Conservation Laws scheme is a 2 order van Leer s scheme In this scheme no upwind information enters the reconstruction WENO Scheme The WENO Weighted Essentially Nonoscillatory scheme is a high order scheme designed for problems with piecewise smooth solutions containing discontinuities The WENO scheme uses adaptive stencils to automatically achieve high order accuracy and non oscillatory properties near discontinuities Reconstructions are done by weighting each of the possible high order stencils from fully upwind to fully downwind In AEROFLO the 5 and 7 order versions of the WENO scheme are implemented The WENO scheme is used for transonic and supersonic flows The 5 order scheme is normally used in house at TTC Compact Scheme The Pad Compact scheme is a high order spatial approach for subsonic flows It is a family of compact high order central type implicit schemes The Compact scheme is inherently non dissipative and more accurate compared to the central type explicit schemes which make it particularly applicable to the simulation of waves with high frequency However the drawback of this scheme is that it may cause oscillations near the region of discontinuity
112. ly solve CFD problems for engineering applications However most of these commercial software packages are of low order CFD simulation accuracy and short of the ability to handle complicated engineering problems These requirements are becoming more and more important in the industries People need a professional and easy to use CFD solution that can solve a large CFD problem while providing high order accurate results AEROFLO was developed to overcome these difficulties AEROFLO takes the advantages of the recently developed CFD fluid models such as large eddy simulation for turbulent flows and high order numerical schemes such as WENO scheme to enable high order CFD simulation to satisfy the increasing requirements for simulation accuracy in industrial applications On the other hand AEROFLO is a multi disciplinary CFD package that consists of CFD solutions for many specific fluid problems such as aeroacoustics combustion magnetohydrodynamics etc This enables AEROFLO to carry out CFD simulations for very complicated engineering projects that may contain various kinds of physics problems AEROFLO can also carry out simulations that involve flows at different regimes ranging from very low to high speeds Finally AEROFLO employs parallel multi block and overset chimera techniques using blocks with generalized coordinates to ensure that very complicated large and realistic problems can be handled At this time AEROFLO is focused on
113. n this chapter we will use the project file created in the last chapter to introduce the AEROFLO input keywords 6 1 A First Look at the Project File In the last chapter we used the AEROFLO GUI to solve a problem of flow through a converging diverging duct By using the GUI environment we set the problem input parameters such as the computational grid information boundary conditions numerical schemes and many other computation control parameters In fact the GUI will automatically save these input parameters in a project file with a special format that can be read and interpreted by the AEROFLO solver It is this project file together with the auxiliary grid files initial files and boundary condition files that will be the inputs for AEROFLO By understanding the structure and format of the project file the user may directly create a new project file or modify an existing project file without using the GUI program In this chapter we will introduce the format of the project file The AEROFLO project file is an ASCH text file consisting of AEROFLO keywords or instructions and data You can open and edit the project file by using any text edit software NotePad WordPad WORD etc Figure 6 1 is the content of the project file cdvduct afl that we created for the flow trough converging diverging duct problem in the last chapter Additional comments and boxes have been added to help you to understand the structure of the file and the me
114. nal B values for MHD calculation where Q is the vorticity is the eddy viscosity is the turbulence kinetic energy is the turbulence kinetic energy dissipation rate w is the turbulence vorticity and B is the B field for the MHD simulation There are other auxiliary result files that include additional information for the flow results 76 An optional TECPLOT result file Cp dat containing the pressure P and pressure coefficient Cp data for the solid wall boundaries if the output format is specified as TECPLOT Arnorm dat file that records the iteration norm for each time step This can be used to check if the calculation is converged AEROFLO also allows the generation of the animation results which include many intermittent results outputted during the calculation It is controlled by the keywords TECANIM and TRANGE under the OUTPUT group keyword For example the following commands in the project file will generate the intermittent result files every 200 steps when the time steps are between 0 and 30000 OUTPUT PRINTFRQ 100 FORMAT TECPLOT TECANIM 1 TRANGE 0 30000 2 END The intermittent result files include CGNS intermittent result files with names res1 cgns where represents the block number between 000 and 999 The intermittent TECPLOT result files with names 1 dat if the output format is TECPLOT The intermittent Cp data files with names Cp1
115. not include post processing and visualization tools However the output results of AEROFLO are well organized and can be processed by most popular post processing and visualization software such as TECPLOT AEROFLO supports the following output formats format PLOT3D format CGNS format AEROFLO also supports the native formats of TTC Technologies other products including INSTED and iSCRIPT 1 4 The Structure of this Manual This manual is divided into several parts Chapter 2 describes the installation procedures for AEROFLO Chapter 3 outlines the general procedures for performing an AEROFLO calculation Chapter 4 describes the AEROFLO GUI environment Chapter 5 explains how to use the AEROFLO GUI to solve a simple problem Chapter 6 describes the input keywords in AEROFLO project files Chapter 7 describes the procedure to run and restart a CFD problem in AEROFLO Chapters 8 and 9 introduce the format of input mesh files and output result files Chapters 10 and 11 explain how to specify the initial and boundary conditions in AEROFLO Chapters 12 and 13 discuss the turbulence models and numerical schemes used in AEROFLO Chapter 14 explains how to implement a parallel calculation Chapter 15 discusses the overset technique used in AEROFLO Chapter 16 contains a complete reference of AEROFLO keywords 2 Installation This chapter details the AEROFLO installation procedures for differ
116. oblem The project file is shown in Figure 14 2 Compared to the single block version of the project file Figure 6 1 only the followings parts have changed There are two BLOCK keywords that are used to load both of the two mesh files boundary conditions are needed to set each of the blocks The inlet boundary conditions are assigned to Block 1 and the outlet boundary conditions are assigned to Block 2 block interface boundary condition is set as the coupling boundary condition The simulation results are shown in Figure 14 3 Comparisons between the two block and single block results are also shown 100 cdvductm afl SGLOBAL TITLE FOLDER SIMTYPE MACH REYNOLDS PR 0 ORDER BCSTYLE SEND SOVERSET SEND STURB TURBTYPE TUVALUE RESET SEND SSPATIAL SCHEME METRIC VISCOUS VISCHEME VISCMON CUTOFFI ISOTROPI ICUT CUTOFFJ ISOTROPJ JCUT SUTHERLN SEND STIMESTEP SCHEME MAXITER GLOBALDT SUBDT GLOBTOL SUBTOL SEND SDAMPING TYPE ES2 54 FES2 FES4 MAXRED OMGAV SRCONST FILTER NFILTER ALPHAN ALPHAl ALPHA2 ALPHA3 ALPHA4 ALPHAS ORDERN ORDER1 ORDER2 ORDER3 ORDER4 ORDERS SEND Converging Diverging Duct cdvductm 2 0 4600000 732676 8 7200000 7 2 r 2 H J H 0 1000000 1 13 172 0 0000001 02 0 o 0 0 0000001 02 0 0 0 3800000
117. og box b In the Procedure list select k e Abid Model c Check to make sure the Turbulence Intensity input box is set to be 0 1 and the Set Initial k e Values button is selected d Click Close to close the Turbulence Modeling dialog box Note If you find the Turbulence Modeling button is disabled go back to the settings of the Spatial Difference Scheme to check if you forgot to select the Viscous button 15 Set Output Parameters In this project we set the output files in TECPLOT format The simulation results are set to be outputted every 500 steps Use the following steps to set the output parameters a Click the Output Parameters button to open the Output Parameters dialog box b In the Output Format drop down menu select TECPLOT c Inthe Output Frequency input box type 500 d Click Close to close the Output Parameters dialog box 16 Save the Project File We have finished all of the settings for this project You can go back to check if each of the settings are correct You can modify all of them After this do not forget to save your project file 5 4 Running the Project in the GUI After the project file is saved the problem can be calculated by clicking the Solve button The Graphics Displays dialog box will show the log information of the simulation including the iteration steps and norms You can use the Stop Pause button to stop pause the calculation To
118. og boxes and the execution of the problem Figure 4 2 is a screen shot of the Main Program Dialog Box elp AEROFLO Multi Disciplinary CFD XI Program Interface ICH Beginner m Expert EEN Load Save Project Problem Setup 9 Aeroelasticity Graphics Display 5 Aeroacoustics Graphics Controls Resume View Results Figure 4 2 Main Program Dialog Box Program Interface The program interface radio buttons allow the user to select the level of user interaction with the program The two available options are Beginner and Expert In Beginner mode the program internally sets defaults for a large portion of the required inputs This mode is recommended for a new user For instance with the compact scheme you do not need to select a scheme because the code will adopt a default high order compact procedure On the other hand the Expert user would specify detailed parameters of the simulation Application The Application group contains the different types of simulations that can be performed with AEROFLO Options include Aeroacoustics Aeroelasticity CEM MHD basic CFD or Navier Stokes and combustion calculations Depending on the license that you have purchased some options may be 22 unavailable The selected application determines the required inputs thus the dialog boxes that are presented to you for data input Load Save Project button This button opens the Load Save Project dialog box where you
119. om C Documents and 5 amples Onera_3B m6wing_v01_b1 grd installation process begins which may take several minutes Program Group Message K d i We are about to create a program group to hold the icons for AEROFLO Please enter a name for it Cancel Help AEROFLO e Create a program group or accept the default Click Installation Completed Message e Congratulations AEROFLO 2 0 has been installed successfully e Installation is successful Click OK Installed Files Once AEROFLO is installed two folders Samples unist three executable files multidisc exe aeroflo exe mpiaeroflo exe and one PDF file aeroflo manual pdf will be installed in the installation directory default is C aeroflo These files or folders are AEROFLO folder samples unist multidisc exe aeroflo exe aeroflo_manual pdf samples contains the AEROFLO sample problems unist contains the AEROFLO uninstall information multidisc exe AEROFLO GUI launch file aeroflo exe sequential AEROFLO solver mpiaeroflo exe parallel AEROFLO solver aeroflo manual pdf AEROFLO User s Manual 2 2 Linux Unix AEROFLO installation on Linux is via the old fashioned command line procedure Please contact TTC for 14 details 15 3 Basic Procedures for CFD Analysis Using AEROFLO In this chapter the basic procedures for a CFD analysis in AE
120. onding error information will be outputted After the solver begins to run the program will output the iteration time step overall physical time and iteration norms of the iterations and sub iterations to let the user know the progress of the computation 78 10 Specifying Initial Conditions In AEROFLO the user can specify initial conditions by an initial condition data file or through global initial conditions specified in the main input file In addition the user can simply accept the default initial conditions 10 1 Default Initial Conditions If no initial conditions are applied to AEROFLO calculations AEROFLO imposes the following initial conditions on the primary variables p 1 0 u 0 v 0 w 0 p 1 10 2 Global Initial Conditions Project File Initial conditions may be applied globally on primary variables using the INITIAL group keyword anywhere in the input file The INITIAL keyword has two sub keywords VARIABLE and VALUE The VARIABLE sub keyword accepts integer values and is the same as those for the boundary conditions commands as reproduced below The VALUE sub keyword accepts real values The primary variable specified by VARIABLE is initially set to the value provided in VALUE prior to the start of the calculations T Densit 1 velocity The following commands present in the main input file for example will set the initial values 79 INITIAL VARIABLE
121. ping function Damping Filtering 5 5 Damping m Filtering Filtering Frequency Figure 4 14 Spatial Damping Filter Dialog Box with Filtering On 35 Spatial Damping Filtering Damping Filtering 3 None m Damping 5 Filtering Boundary Layer Damping 1 Damping Coeffs 0 200000E 00 0 100000E 01 Imp Damping Coeffs 0 100000E 01 0 200000E 01 Imp Damping Modifiers 0 100000 01 0 000000 00 Close Figure 4 15 Spatial Damping Filter Dialog Box with Damping On Turbulence Modeling button This button opens the Turbulence Modeling dialog box which is used to specify the turbulence model Figure 4 16 is a screen shot of this dialog box The Procedure dialog box lists the turbulence models supported by AEROFLO These options are LES Smagorinsky with compact differencing of the LES terms LES Smagorinsky with 2 9 differencing of the LES terms LES Smagorinsky with 1st order differencing of the LES terms LES Dynamic model Spalart Allmaras one equation model ke Launder Sharma model k e Abid model Menter s SST model k e High Reynolds No model DES Based on Spalart Allmaras model PRNS Based on Abid k e model PRNS Based on High Re k e model The Turbulence Intensity input box sets the value of the inlet turbulence intensity for the k e models The Set Initial k e Values button generates initial conditions for k e values using
122. providing professional CFD solutions in the applications of aeronautics and astronautics Therefore AEROFLO only handles the simulation of gas flows 1 2 Capabilities and Features AEROFLO is a high order multi disciplinary computational fluid dynamics solver package AEROFLO can perform the following kinds of simulations CFD Solution of Navier Stokes Equations Magnetohydrodynamics MHD Aeroacoustics Combustion Aeroelasticity Electromagnetics Hypersonic Flows Figure 1 1 at the end of this section summarizes the program capabilities of AEROFLO AEROFLO contains various turbulent models to meet the different kinds of simulation requirements Reynolds Averaged Navier Stokes model RANS Spalart Allmaras model Abid s k e model Launder Sharma model Menter s SST k w model High Reynolds number model Large Eddy Simulation model LES Smagorinsky model Dynamic model Direct Numerical Simulation model DNS Hybrid model Detached Eddy Simulation DES based on Spalart Allmaras model Partially Resolved Numerical Simulation PRNS based on Abid s model AEROFLO can handle flows at all speed regimes subsonic transonic supersonic and hypersonic To perform these simulations the package incorporates the following numerical solution schemes Various high order spatial schemes type compact scheme 6 for low speed
123. resume a 49 paused calculation simply click the Resume button 5 5 Simulation Results The computation will take several hours After the calculation is finished you can check the simulation results In this problem we specify the TECPLOT format as the format of the output result If the TECPLOT software is already installed in your system you may view the result by clicking View Results If you prefer to use other visualization tools you can launch the software outside of AEROFLO and find the result files in the project subfolder directory Figure 5 3 is the simulation result of the Mach number contours for the flow field Ma 0 10 0 19 0 29 0 38 0 48 0 58 0 67 0 77 0 87 0 96 1 06 1 15 1 25 1 35 Figure 5 3 Mach Number Contour for Flow Through a Converging Diverging Duct 5 6 Remarks By following the above tutorial you have learned the basic procedures to solve a CFD problem in AEROFLO and should now be familiar with the AEROFLO GUI Indeed the AEROFLO GUI provides an environment by which the user can easily set the input parameters for AEROFLO All of these parameters are saved in a project file In the next chapter we will use the project file created in this chapter to study the detailed structures of a project file By understanding the meaning of each keyword in the project file the user can modify or even create a project file directly without using the GUI program 6 Introduction to AEROFLO Input Keywords I
124. riable is used to control filtering in each of the three directions This variable takes on a value of either 0 or 1 When the value is 1 filtering is done in that direction Otherwise filtering is not performed For example FILTER 1 1 0 will result in filtering in the i and j directions only if the filtering option is chosen as the damping type TYPE 4 or TYPE 3 NFILTER This variable determines the number of times that filtering will be performed each time For example NFILTER 2 2 0 will result in filtering twice in the i and j direction for each round of filtering For instance if damping TYPE 3 filtering will be performed twice after every sub iteration or twice after every iteration if damping TYPE A ORDERN ORDERS ORDER4 ORDER3 ORDER2 ORDERI These variables control the order of accuracy of filters in the interior nodes fifth fourth third second node 127 from the boundary and boundary nodes respectively The values are specified for all three directions ORDERN 10 10 0 ORDERS 8 8 0 ORDER4 6 6 0 ORDER3 4 4 0 ORDER2 2 2 0 ORDER1 0 0 0 The above specification will use a tenth order filter at the interior nodes and eighth sixth fourth order and second order filters at the fifth fourth third and second nodal points from the boundary while no filtering will be performed at the boundary nodes Please consult the appendix for notes and tables on acceptabl
125. s ANGLE Maximum angle at which a node lying close to a solid boundary may be projected DISTANCE Maximum distance that a node lying close to a solid boundary may be projected 133 16 9 FACEBC Keywords The sub keywords in the FACEBC keyword block specify a surface boundary condition This input group may appear several times Each occurrence specifies a unique boundary condition BLOCK Name of the block to which the boundary condition refers BCSTYLE There are two styles to label the side of the block See SIDE SIDE If BCSTYTLE 1 side of the block to which the boundary condition refers 1 k KE 2 i IE 3 k 1 4 i 1 5 6 2 If BCSTYTLE 2 side of the block to which the boundary condition refers 1 i 1 1 i IE 2 j 1 2 j JE 3 k 1 3 k KE TYPE The list of the available boundary condition types are listed in the table below 1 Solid Wall 2 Coupling 3 Overset boundary condition 8 Coupling due to periodicity 9 1 1 C Grid Dirichlett Symmetry o 13 Symmetry in any plane 134 14 Symmetry in j any plane 15 Symmetry in k any plane 23 Neumann 0 flux 24 Specified flux 30 Inflow 31 Outflow 32 Free stream 41 Characteristic Inflow B C 42 Characteristic Outflow B C 52 Initial value 59 Singular point surface e g sphere grid 60 i axes axisymmetric
126. s derivative terms will be computed as well SUTHERLN Sutherland s law parameter Choosing a negative value results in an inviscid calculation Choosing a value greater than 9999 means that the viscosity is considered constant and Sutherland s law does not applied COMPACTI This input specifies the compact scheme for differencing in the direction Used if SCHEME 15 in the I direction this character variable consists of five fields designating the scheme to be employed at points 1 2 interior N 1 and N respectively For instance C4 CC4 C6 ACA C4 requests the fourth order compact scheme at point 1 the decoupled fourth order compact scheme at point 2 compact sixth order in the interior the symmetric compact fourth order scheme at point N 1 and the fourth order compact scheme at point N Note For efficiency if the interior scheme is explicit the tridiagonal system is not solved resulting in faster solutions However it is not possible to combine explicit interior schemes with implicit boundary schemes Please consult the appendix for tables and descriptions of the filtering schemes This input specifies the compact scheme for differencing in the J direction See the notes for COMPACTK This input specifies the compact scheme for differencing in the K direction See the notes for COMPACTI COMPACTG This input specifies the compact scheme for the grid differencing See the notes for COM
127. s variable BFIELD four dimensional arrays exactly of size IL JL KL 3 for the MHD B field variables A FORTRAN 90 segment for writing a grid in the AEROFLO format for a CFD Navier Stokes calculation is shown below REAL DIMENSION IL JL KL U V W RHO P Generate the mesh of size IL JL KL OPEN 2 FILE test in FORM UNFORMATTED statusz REPLACE TINIT 0 0 WRITE 2 IL JL KL O TINIT U V W P RHO CLOSE 2 The commands to load this file for initial conditions in the main input file are BLOCK mesh0 MESHFILE grid dat FILETYPE PLOT3D ICFILE test in END Note The specifications of an initial condition file supersede the global initial conditions specified in the main input file 81 10 4 Setting the Initial Conditions in Block Data Files As we mentioned in Chapter 7 the restart file is a special block data file that contains the previous calculation results This can be extended to the general cases that the user can write a block data file which includes specified flow initial conditions for each of mesh node points The command to specify this file with a block description is BLOCK MESHFILE There is need to use the ICFILE keyword in this case anymore A FORTRAN 90 segment to write a grid in the AEROFLO format for a CFD calculation is shown below REAL DIMENSION IL JL KL X Y Z U V W RHO P Generate the mesh of size IL JL KL OPEN 2 FILE
128. se Paper AIAA 2008 0011 46 Aerospace Sciences Meeting and Exhibit Reno January 6 10 2008 Cai X and Ladeinde F 2008 Performance of WENO Scheme on Generalized Curvilinear Coordinate Systems Paper AIAA 2008 0036 46 AIAA Aerospace Sciences Meeting and Exhibit Reno January 6 10 2008 Ladeinde 2008 Further Development of a High Order Prediction Tool for Combustion at All Speeds Paper ATAA 2008 0510 46th AIAA Aerospace Sciences Meeting and Exhibit Reno January 6 10 2008 Cai X Ladeinde F and Alabi K 2007 Hybrid RANS LES Calculations of High Speed Jet Noise 2007 3870 37th Fluid Dynamics Conference and Exhibit Miami Florida June 25 28 2007 Cai X and Ladeinde F 2007 A Hybrid LES RANS Calculation of Subsonic and Supersonic Hot Jet Noise GT2007 28117 Turbo Expo 2007 Montreal Canada May 14 17 2007 Alabi K Ladeinde F 2007 High Order Dynamic Overset Procedure Applied to Moving Body Calculations AIAA Paper AIAA 2007 248 45th Aerospace Sciences Meeting and Exhibit Reno Jan 08 11 2007 Safta C Alabi K Ladeinde F Cai X 2007 A Combined Level Set Mixture Fraction Progress Variable Approach for Partially Premixed Turbulent Reacting Flows AIAA Paper AIAA 2007 1436 45th AIAA Aerospace Sciences Meeting and Exhibit Reno NV Jan 08 11 2007 Cai X Ladeinde F Alabi K 2007 Towards Predicting Supersonic Hot Jet Noise AI
129. stics Calculation Subsonic transonic and supersonic turbulent flow Adjoint Green function procedure to calculate sound pressure level Realistic engineering problems High order at all speeds Combustion Calculation Level set flamelet LES procedure Premixed non premixed and partially premixed flames Realistic engineering problems Arbitrary complex kinetic mechanisms High order at all speeds Magnetogasdynamics Calculation Full blown magnetic induction equations available Source formulation Realistic engineering geometries High order at all speeds Hypersonic flow Calculation Continuum method for non equilibrium flows Particle method for non equilibrium flows Hybrid method for non equilibrium flows Figure 1 1 Capabilities of AEROFLO and its Main Features 1 3 Program Structure Your AEROFLO package includes the following programs AEROFLO GUI Sequential AEROFLO solver Parallel AEROFLO solver Manuals and sample problem files AEROFLO does not include grid generation tools However AEROFLO supports most common grid formats and therefore supports the grids generated by most grid generation software Computational mesh formats supported in AEROFLO include PLOT3D format CGNS format CGNS stands for CFD General Notation Scheme and is an widely accepted industry standard for CFD data AEROFLO native format AEROFLO also does
130. tends the cut to the boundary of both ends and leaves no overlap In particular for 30 problems the cut is intended to extend through the periodic direction 4 The cut extends to i j or k 1 without any offset or overlap 5 The cut extends to i j or k End without any offset or overlap In the example below which represents a 2D two block setup with injection of the wall boundary of BLOCK2 the grid BLOCK 1 blanks all regions of BLOCK2 overlapping it all the way to the wall region BLOCK2 MESHCUT CUTTER BLOCK2 BLOCKS BLOCK1 PERIODICITY 0 4 3 END 114 16 AEROFLO Input Keywords In this chapter the keywords expected values and default values of input AEROFLO parameters are described A summary of group keywords in AEROFLO is shown below Keywords of global scope include GLOBAL TURB MHD SPATIAL TIMESTEP DAMPING POISSON CASESPEC OUTPUT DEBUG global project data including simulation type project folder project files and flow parameters such as Reynolds number Mach number etc specifies turbulence data When not provided no turbulence model is activated for the problem specifies MHD data Required for MHD simulation types SIMTYPE 5 or 6 spatial differencing data time differencing data damping or filtering data When not provided no damping or filtering is applied Poisson solver data Required for MHD
131. test in FORM UNFORMATTED statusz REPLACE 0 0 WRITE 2 IL JL KL O TINIT X Y Z U V W P RHO CLOSE 2 Compared to the example given in the last section the only difference is that the grid information x y z is also written to the file The commands to load this file for initial conditions in the main input file are BLOCK NAME mesh0O MESHFILE test in FILETYPE AEROFLO ICFILE NULL END 82 11 Specifying Boundary Conditions AEROFLO solves CFD problems in a multi block format This means that the domain of the CFD problem may contain several structured blocks Since the blocks are structured each block will consist of six boundary faces For the problem to be complete boundary conditions must be specified on all faces of a block The boundary conditions may range from simple boundary conditions such as Dirichlett or Neumann to compound boundary conditions such as free stream inlet or outflow boundary conditions The main difference between simple and compound boundary conditions is that simple conditions act on a specific variable while compound boundary conditions have a compound equation for all the variables at the boundary To apply boundary conditions on a face of a block the FACEBC group keyword is used The BLOCK keyword indicates the block to which the boundary condition applies The SIDE keyword indicates the face of the block to which the condition
132. the inlet turbulence intensity 36 Turbulence Modeling Procedure k e Launder Sharma model 5 SST model k e High Reynolds No model DES Based on Spalart Allmaras model PRNS Based on Abid k e model Turbulence Intensity 0 10000 00 Set Initial k e Values Close Figure 4 16 Turbulence Modeling Dialog Box Output Diagnostic Parameters button This button opens an Output Diagnostic Parameters dialog box which is used to specify the output parameters Figure 4 17 is a screen shot of this dialog box The Output Format drop down menu selects the format of the output files The supported formats are CGNS TECPLOT and PLOT3D The Output Frequency input box controls the number of time steps at which the output is written The Save Output Histories button is used to indicate if history files are saved and the associated input for the frequency of save The History Save Start End input boxes and the Every xN times drop down menu control the output period and frequency of the history files The Average buttons are used to generate average results at a point The average is computed using the solutions generated between time steps Start and End The Diagnostic Point in I J K input boxes select the point at which the diagnostic values of the solution are printed in the log screen or Display dialog box 37 Output Diag meters Output Format Output Frequency 0 5 Save Output Histories
133. tion Last I Face 0 Boundary Condition Last I Face P 3 26325 FACEBC Boundary Condition First J Face Solid Wall FACEBC Boundary Condition Last J Face Solid Wall I NITI AL Initial Condition u 1 I NITI AL Initial Condition v 0 I NITI AL Initial Condition p 1 Figure 6 1 The Project File cdvduct afl for Flow Through Converging Diverging Duct Cont SEND SINITIAD I NITIAL VARIABLE 5 VALUE 3 375640 Initial Condition SEND P 3 37564 Figure 6 1 The Project File cdvduct afl for Flow Through Converging Diverging Duct Cont 55 6 2 Structure of the Project File Let s look at the project file now The first line is the name of the project file After that the file consists of several blocks In Figure 6 1 these blocks are highlighted and distinguished from each other by using green boxes Each of these blocks starts with a keyword that has a in front of it such as GLOBAL TURB SPATIAL TIMESTEP BLOCK FACEBC INITIAL etc These keywords are called group keywords The keyword END is used to end a block By using this block structure the AEROFLO input parameters are categorized into several groups For example the GLOBAL block specifies global project data including simulation type project folder and flow parameters such as Reynolds number and Mach number Some group keywords are necessary for every problem such as GLOBAL SP
134. tions 4 Dynamic SGS This choice requires the specification of homogenous directions 5 Spalart Allmaras This choice also requires the specification of trip points along the solid walls of the model Launder Sharma k amp model Abid s model Menter s SST k w model High Reynolds Number model 10 DES based on Spalart Allmaras 11 PRNS based on Abad s 12 PRNS based on high Reynolds DIRECTN Homogenous directions For instance 1 0 0 means homogenous in the direction only This input is required for TURBTYPE 4 NUMTRIPS Number of trip points on solid surfaces This input is required for TURBTYPE 5 NUMTRIPS 2 The above specification means that two trip points will be employed at the solid wall surfaces of the mesh 118 See the sample problem cylinder txt The keyword is scheduled to be returned If not provided the trip points are automatically coded to be at the start of the boundary layer POINT The trip points are specified as x y z for as many trip points as NUMTRIPS Each point is separately specified on its own line PLANE Description of the symmetry plane x y z via three points specified as x y z For O grids points on opposite sides of this plane are not affected by trip points on the other side For grids in which all the points lie on the same side of the solid wall the plane should be defined below the wall so that all points li
135. u can double click the multidisc exe in AEROFLO s installation directory or find the Programs gt AEROFLO gt AEROFLOGUPF in the Start menu 4 1 GUI Components AEROFLO s User Interface is made up of four main components Main Program Dialog Box Program Setup Dialog Box Graphics Display Dialog Box and Graphics Controls Dialog Box Users interact with these components to set up an AEROFLO project Figure 4 1 is a complete screen shot of the AEROFLO GUI The details of each component will be described in subsequent sections multidisc INSTED The Software You Will Always Use Graphics Display rogram Interface dr Application 9 Aeroacoustics 1 ercelasticity 1 3 E Global Flow Conditions Manage Grid Blocks Initial Conditions Time Integration Scheme Spatial Differencing Scheme Spatial Damping Filtering 2 Modeling 4 Help Graphics Controls Status Bar 4 Running input pending INSTED The Software You Will Always Use Figure 4 1 AEROFLO GUI Components 1 Main Program Dialog Box 2 Program Setup Dialog Box 3 Graphics Display Dialog Box 4 Graphics Controls Dialog Box 21 4 2 Main Program Dialog Box The Main Program Dialog Box contains the most basic controls for AEROFLO simulations such as the selection of the simulation type the project file manipulation controls to the other dial
136. uch as WINZIP or WINRAR for this step In the folder where you unzipped the installation file go to the run subfolder and double click setup exe The installation interface will be shown 11 Welcome Message d i This program will install AEROFLO 2 0 beta onto your system Copyright 1993 2006 Thaerocomp Technical Corporation Don t Install Help e Click Install User Information Message Thank you for choosing this product Please enter your name below User name Company name e Enter the User name and Company name then click OK Message d i Please enter the directory where the files of AEROFLO 2 0 will be copied to Cancel To accept the default press enter Help e Select the installation path or leave it as the default value C laeroflo Click OK Message d i your screen resolution above or equal to 1024x768 12 e The AEROFLO GUI requires that the screen resolution be 1024x768 or better for optimum performance Adjust the resolution if it is not and then click Yes Message d i Please indicate the version of MPI you have installed Enter 0 E for MPICH and 1 for MPIPRO e Enter 0 if MPICH is installed or 1 if MPIPRO is installed Leave the default value if MPICH is installed Click OK AEROFLO 2 0 Decompressing Fr
137. ues 0 1 and 2 No periodicity 1 Periodic 2 Periodic but no overlap 3 2D Convert to 3D in this direction AEROFLO solves periodicity with the expected overlap of at least five grid points in the periodic direction If the mesh was generated such that the last node point is the same as the first node point then there is no overlap and the user must specify a periodic value of 2 to ensure that AEROFLO appropriately overlaps the grid PERIODIC 1 0 1 The above specification for example describes a block that is periodic in i and k If a block is degenerate or 2D in one direction the user should specify periodicity in this direction This ensures that the same results are maintained at all nodes Note that the current program does not permit 2D definition by using only one node and at least three nodes must be specified in the degenerate direction If the mesh is 2D the PERIODIC indicator must be 3 in the 2D direction to ensure that AEROFLO properly generates 2 extra nodes in this direction Also remember to set the SSPATIAL SCHEME value to 999 in a degenerate direction ORDER Number of nodes required at the boundary for overset formulation If not specified assumes the default global value of 2 DONORS List of other blocks that possibly overlap the block being specified This list must use the block names to refer to the donor blocks Ensure that all blocks on this list are also described with the BLOCK command
138. urbulence Modeling dialog box will not be accessible if you asked for an inviscid simulation for all blocks in the project Dialog boxes that have been opened and for which inputs have been provided are disabled grayed to indicate that they have been processed This helps your book keeping To return to a grayed dialog box you simply click the Edit button on the right of the button that you wish you access MHD Solver Parameters Poisson Solver Parameters Figure 4 4 Problem Setup Dialog Box Global Flow Conditions button This button opens up the Global Flow Variables dialog box which is used to specify the global flow parameters Figure 4 5 is a screen shot of the Global Flow Variables dialog box In AEROFLO variables can be specified in either dimensional or non dimensional form 25 0 000000 00 0 720000 00 0 000000 00 Figure 4 5 Global Flow Variables Dialog Box Nondimensional global flow parameters include Mach number Prandtl number and Reynolds number The dimensional global flow parameters include conductivity density length scale pressure specific heat temperature velocity and viscosity A screen shot of the inputs of dimensional flow parameters are shown in Figure 4 6 Note that the Obtain Properties from INSTED Database button opens up TTC s INSTED database to import the thermophysical properties of hundreds of liquids and gases over a range of temperatures 26 Global Flow Vari
139. ure of the Navier Stokes equations the averaged equations will always contain additional unknown terms that depend on the fluctuating components of the variables leading to the so called turbulence closure problem Before closure models are introduced we always have more unknown variables than equations Thus to close the averaged equations we need to provide additional equations that can model the influence of the fluctuating quantities on the mean quantities Many turbulence models have been developed to different levels of fidelity and robustness 12 2 Reynolds Averaged Navier Stokes RANS The Reynolds averaged Navier Stokes RANS models include the following one equation Spalart Allmaras or two equation models k e Spalart Allmaras Model In this model single modeled transport equation is solved for the turbulent viscosity In this case it is not necessary to calculate another length scale using an algebraic equation The Spalart Allmaras model is 89 computationally simpler than two equation models Launder Sharma k s model This is a two equation low Reynolds number k e model The phrase ow Reynolds number refers to the fact that the local turbulence Reynolds number is small in the region close to wall due to the strong viscous effects it does not mean that the global Reynolds number is small In the low Reynolds number model the k e equations and the calculation are modified using certain
140. wall computations The main idea of the wall function approach is to apply boundary conditions some distance away from the wall so that the turbulence model equations do not need to be solved close to the wall The procedures for RANS simulation in AEROFLO are shown in Figure 12 1 90 RANS model ee er Soe ee Cee ets ees Instantaneous Navier Stokes Solve k equation and Equations equation w equation Reynolds Averaging Y Reynolds Averaged Navier Stokes Equations Unclosed term Reynolds Stress Calculate eddy viscosity from k and w Numerical i Solver Calculate Reynolds stresses from eddy viscosity Mean flow properties Figure 12 1 Procedures for RANS simulation in AEROFLO 12 3 Large Eddy Simulation LES Kolmogorov s theory indicates us that the large eddies in turbulent flows are influenced by the flow geometries and that the small scale eddies have a universal character Therefore it is reasonable to resolve only the large scale flow properties and model the small scale eddies based on the larger ones This method is called Large Eddy Simulation LES In LES a function is used to filter the Navier Stokes equation The LES procedure decomposes the primary variables into filtered components large scale value and small scale subgrid scale components with additional unclosed sub grid scale SGS
141. will be applied The TYPE keyword specifies the type of boundary conditions A list of the currently supported types of boundary conditions is included below The VALUE keyword specifies the value of the boundary condition It is required for types such as Dirichlett or free stream The VARIABLE keyword specifies the solution variable to apply the boundary condition on It is required for simple boundary condition types The boundary condition commands may be invoked several times anywhere in the main input file 11 1 Boundary Precedence Rules The precedence of the boundary conditions is as follows 23 Neumann 24 Specified flux 32 Subsonic free stream 31 Subsonic outflow 71 Slip wall 30 Subsonic inflow 1 No ship wall 80 Equation 10 Dirichlett 83 41 Characteristic inflow boundary condition 42 Characteristic outflow boundary condition Boundary conditions of the same type are simply applied in the order in which they are specified in the input file For this reason the user should exercise care in specifying the boundary conditions 11 2 AEROFLO Boundary Condition Types For all of the boundary condition equations below Density u velocity v velocity w velocity Pressure 11 2 1 Simple Boundary Conditions Dirichlett Type 10 This applies a fixed value to the surface nodes indicated d f fis some real number Specifying this boundary condition requires the following BLOCK SIDE TYPE V
142. wnloaded at http sourceforge net projects cgns PLOT3D File Format The PLOT3D format is used to convey three dimensional structured grid information Exporting meshes in the PLOT3D format is supported by most grid generation software AEROFLO only supports PLOT3D files in an ASCII formatted and multi block format The data type in the PLOT3D file can be single or double precision For PLOT3D grid files the format is nblock number of zones in files zone 1 i dim j dim k dim zone 2 i dim j dim k dim zonen i dim j dim k dim zone 1 all x values all y values all z values zone 2 all x values all y values 71 all z values zone all x values all y values all z values For PLOT3D solution files Q files the format is nblock number of zones in files zone 1 i dim j dim k dim zone 2 i dim dim k dim zonen i dim j dim k dim zone 1 mach freestream Mach number alpha freestream angle of attack re freestream Reynolds number time time all u values all v values all w values all P values all rho values zone 2 mach freestream Mach number alpha freestream angle of attack re freestream Reynolds number time time all u values all v values all w values all P values all rho values zone n mach freestream Mach number alpha freestream angle of attack re freestream Reynolds number time time all u values all v values all w values all P values a
143. would be an input line for a coordinate point All real data type input must have a For example MACH 0 2 MACH 2 0 String inputs should be within single string quotes of the type shown the example below MESHFILE ffoil in However input into AEROFLO via an input file affords the following flexibility Extra lines and spaces be inserted anywhere Comments and notes be inserted anywhere However it is probably good practice to insert comments outside of keyword input blocks KEY END sections Inputs that not relevant to a particular problem do not need to be provided Input may be provided in any order For example BLOCK NAME mesh0 MESHFILE meshO dat 57 ISIZE 245 JSIZE 50 END would be read the same as BLOCK NAME mesh0 ISIZE 245 JSIZE 50 MESHFILE meshO0 dat END Keyword input blocks may be ordered as desired For instance block inputs may be entered at the top of the files while global inputs are at the bottom but the global data would still be read first This allows the user to make up input files easily by copying and modifying whole blocks from other input or sample files 58 GLOBAL Global project data TITLE Specify a title for the project for information purposes FOLDER Subfolder directory folder from which input files will be read SIMTYPE

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