ANSYS CFX Reference Guide

402 Pages·2013·8.09 MB·English

ANSYS CFX Reference Guide
ANSYS, Inc. Release 15.0
Southpointe November 2013
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Table of Contents
1. ANSYS CFX Launcher.............................................................................................................................. 1
1.1.The ANSYS CFX Launcher Interface.................................................................................................... 1
1.1.1. Menu Bar................................................................................................................................. 1
1.1.1.1. File Menu........................................................................................................................ 1
1.1.1.1.1. Save As................................................................................................................... 1
1.1.1.1.2. Quit........................................................................................................................ 1
1.1.1.2. Edit Menu ....................................................................................................................... 2
1.1.1.2.1. Clear....................................................................................................................... 2
1.1.1.2.2. Find........................................................................................................................ 2
1.1.1.2.3. Options .................................................................................................................. 2
1.1.1.2.3.1. User Interface Style........................................................................................ 2
1.1.1.2.3.2. Application Font and Text Window Font.......................................................... 2
1.1.1.3. CFX Menu....................................................................................................................... 2
1.1.1.3.1. CFX-Pre .................................................................................................................. 2
1.1.1.3.2. CFX-Solver Manager............................................................................................... 2
1.1.1.3.3. CFD-Post ................................................................................................................ 2
1.1.1.3.4. Other CFX Applications........................................................................................... 2
1.1.1.4. Show Menu..................................................................................................................... 3
1.1.1.4.1. Show Installation.................................................................................................... 3
1.1.1.4.2. Show All................................................................................................................. 3
1.1.1.4.3. Show System.......................................................................................................... 3
1.1.1.4.4. Show Variables ....................................................................................................... 3
1.1.1.5.Tools Menu...................................................................................................................... 3
1.1.1.5.1. ANSYS Client Licensing Utility................................................................................. 3
1.1.1.5.2. Command Line....................................................................................................... 3
1.1.1.5.3. Configure User Startup Files (Linux only)................................................................. 4
1.1.1.5.4. Edit File .................................................................................................................. 4
1.1.1.5.5. Edit Site-wide Configuration File............................................................................. 4
1.1.1.6. User Menu....................................................................................................................... 4
1.1.1.7. Help Menu...................................................................................................................... 4
1.1.2.Tool Bar.................................................................................................................................... 4
1.1.3.Working Directory Selector....................................................................................................... 4
1.1.4. Output Window....................................................................................................................... 5
1.2. Customizing the ANSYS CFX Launcher.............................................................................................. 5
1.2.1. CCL Structure........................................................................................................................... 5
1.2.1.1. GROUP............................................................................................................................ 5
1.2.1.2. APPLICATION................................................................................................................... 6
1.2.1.2.1. Including Environment Variables............................................................................. 8
1.2.1.3. DIVIDER........................................................................................................................... 8
1.2.2. Example: Adding the Windows Calculator................................................................................. 8
2.Volume Mesh Import API........................................................................................................................ 9
2.1.Valid Mesh Elements in CFX............................................................................................................... 9
2.2. Creating a Custom Mesh Import Executable for CFX-Pre................................................................... 10
2.2.1. Compiling Code with the Mesh Import API............................................................................. 11
2.2.2. Linking Code with the Mesh Import API.................................................................................. 11
2.2.2.1. Linking a Customized C Mesh Import Executable on a UNIX Platform.............................. 11
2.2.2.2. Linking a Customized Fortran Mesh Import Executable on a UNIX Platform..................... 12
2.2.2.3. Linking a Customized Mesh Import Executable on a 32-bit Windows Platform................. 12
2.2.2.4. Linking a Customized Mesh Import Executable on a 64-bit Windows Platform................. 12
2.3. Details of the Mesh Import API........................................................................................................ 12
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2.3.1. Defined Constants.................................................................................................................. 13
2.3.1.1. Element Types............................................................................................................... 13
2.3.1.2. Region Types................................................................................................................. 13
2.3.2. Initialization Routines............................................................................................................. 14
2.3.2.1. cfxImportStatus............................................................................................................. 14
2.3.2.2. cfxImportInit ................................................................................................................. 14
2.3.2.3. cfxImportTest................................................................................................................ 14
2.3.3.Termination Routines............................................................................................................. 15
2.3.3.1. cfxImportDone.............................................................................................................. 15
2.3.3.2. cfxImportTotals ............................................................................................................. 15
2.3.4. Error Handling Routines......................................................................................................... 15
2.3.4.1. cfxImportError............................................................................................................... 15
2.3.4.2. cfxImportFatal............................................................................................................... 16
2.3.5. Node Routines....................................................................................................................... 16
2.3.5.1. cfxImportNode.............................................................................................................. 16
2.3.5.2. cfxImportGetNode ........................................................................................................ 16
2.3.5.3. cfxImportNodeList......................................................................................................... 16
2.3.6. Element Routines................................................................................................................... 16
2.3.6.1. cfxImportElement.......................................................................................................... 16
2.3.6.2. cfxImportGetElement.................................................................................................... 18
2.3.6.3. cfxImportElementList .................................................................................................... 18
2.3.6.4. cfxImportGetFace.......................................................................................................... 18
2.3.6.5. cfxImportFindFace......................................................................................................... 19
2.3.7. Primitive Region Routines....................................................................................................... 19
2.3.7.1. cfxImportBegReg .......................................................................................................... 19
2.3.7.2. cfxImportAddReg.......................................................................................................... 20
2.3.7.3. cfxImportEndReg .......................................................................................................... 20
2.3.7.4. cfxImportRegion ........................................................................................................... 20
2.3.7.5. cfxImportRegionList...................................................................................................... 20
2.3.7.6. cfxImportGetRegion...................................................................................................... 20
2.3.8. Composite Regions Routines.................................................................................................. 21
2.3.8.1. cfxImportBegCompRegion ............................................................................................ 21
2.3.8.2. cfxImportAddCompRegComponents............................................................................. 21
2.3.8.3. cfxImportEndCompReg................................................................................................. 21
2.3.8.4. cfxImportCompositeRegion........................................................................................... 21
2.3.9. Explicit Node Pairing.............................................................................................................. 21
2.3.9.1. cfxImportMap ............................................................................................................... 22
2.3.10. Fortran Interface .................................................................................................................. 22
2.3.10.1. cfxinit.......................................................................................................................... 22
2.3.10.2. cfxtest......................................................................................................................... 22
2.3.10.3. cfxunit......................................................................................................................... 22
2.3.10.4. cfxwarn....................................................................................................................... 22
2.3.10.5. cfxfatl.......................................................................................................................... 22
2.3.10.6. cfxdone....................................................................................................................... 22
2.3.10.7. cfxnode....................................................................................................................... 23
2.3.10.8. cfxnodg....................................................................................................................... 23
2.3.10.9. cfxnods ....................................................................................................................... 23
2.3.10.10. cfxelem ..................................................................................................................... 23
2.3.10.11. cfxeleg ...................................................................................................................... 23
2.3.10.12. cfxeles....................................................................................................................... 23
2.3.10.13. cfxfacd ...................................................................................................................... 23
2.3.10.14. cfxface....................................................................................................................... 24
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2.3.10.15. cfxffac ....................................................................................................................... 24
2.3.10.16. cfxregn...................................................................................................................... 24
2.3.10.17. cfxregb...................................................................................................................... 24
2.3.10.18. cfxrega...................................................................................................................... 24
2.3.10.19. cfxrege...................................................................................................................... 24
2.3.10.20. cfxregs ...................................................................................................................... 25
2.3.10.21. cfxregg...................................................................................................................... 25
2.3.10.22. cfxcmpb.................................................................................................................... 25
2.3.10.23. cfxcmpa .................................................................................................................... 25
2.3.10.24. cfxcmpe .................................................................................................................... 25
2.3.11. Unsupported Routines Previously Available in the API........................................................... 25
2.4. An Example of a Customized C Program for Importing Meshes into CFX-Pre..................................... 26
2.5. Import Programs ............................................................................................................................ 26
2.5.1. ANSYS.................................................................................................................................... 26
2.5.2. CFX Def/Res........................................................................................................................... 27
2.5.3. CFX-4..................................................................................................................................... 27
2.5.4. CFX-5.1.................................................................................................................................. 27
2.5.5. CFX-TfC.................................................................................................................................. 29
2.5.6. CGNS..................................................................................................................................... 29
2.5.6.1. SplitCGNS.exe................................................................................................................ 30
2.5.7. Fluent.................................................................................................................................... 30
2.5.8. GridPro/az3000...................................................................................................................... 30
2.5.9. I-DEAS ................................................................................................................................... 31
2.5.10. ICEM CFX............................................................................................................................. 31
2.5.11. PATRAN................................................................................................................................ 31
2.5.12. NASTRAN............................................................................................................................. 32
2.5.13. CFX-TASCflow ...................................................................................................................... 32
3. Mesh and Results Export API................................................................................................................ 33
3.1. Creating a Customized Export Program........................................................................................... 33
3.1.1. An Example of an Export Program.......................................................................................... 34
3.1.1.1. File Header.................................................................................................................... 34
3.1.1.2. Allowed Arguments....................................................................................................... 34
3.1.1.3. Main Program Initialization............................................................................................ 34
3.1.1.4. Checking File Names..................................................................................................... 36
3.1.1.5. Opening the CFX Results File......................................................................................... 36
3.1.1.6.Timestep Setup............................................................................................................. 37
3.1.1.7. Geometry File Output.................................................................................................... 38
3.1.1.8.Template Results File..................................................................................................... 40
3.1.1.9. Creating Files with Results for Each Variable................................................................... 41
3.1.2. Example of Output Produced................................................................................................. 43
3.1.2.1. example.geom .............................................................................................................. 43
3.1.2.2. example.res................................................................................................................... 44
3.1.2.3. example.s01.................................................................................................................. 44
3.1.3. Source Code for getargs.c....................................................................................................... 44
3.2. Compiling Code with the Mesh and Results Export API.................................................................... 45
3.3. Linking Code with the Mesh and Results Export API......................................................................... 45
3.3.1. UNIX...................................................................................................................................... 46
3.3.2.Windows (32-bit).................................................................................................................... 46
3.3.3.Windows (64-bit).................................................................................................................... 46
3.4. Details of the Mesh Export API........................................................................................................ 46
3.4.1. Defined Constants and Structures........................................................................................... 47
3.4.1.1. Element Types............................................................................................................... 47
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3.4.1.2.Volume List Types.......................................................................................................... 47
3.4.1.3. Region List Types........................................................................................................... 47
3.4.1.4. Count Entries................................................................................................................. 47
3.4.1.5. Node Data Structure...................................................................................................... 48
3.4.1.6. Element Data Structure.................................................................................................. 48
3.4.2. Initialization and Error Routines.............................................................................................. 48
3.4.2.1. cfxExportInit.................................................................................................................. 48
3.4.2.2. cfxExportDone .............................................................................................................. 48
3.4.2.3. cfxExportError ............................................................................................................... 49
3.4.2.4. cfxExportFatal ............................................................................................................... 49
3.4.3. Zone Routines........................................................................................................................ 49
3.4.3.1. cfxExportZoneCount ..................................................................................................... 49
3.4.3.2. cfxExportZoneSet.......................................................................................................... 49
3.4.3.3. cfxExportZoneGet ......................................................................................................... 50
3.4.3.4. cfxExportZoneFree ........................................................................................................ 50
3.4.3.5. cfxExportZoneIsRotating ............................................................................................... 50
3.4.3.6. cfxExportZoneMotionAction.......................................................................................... 50
3.4.4. Node Routines....................................................................................................................... 50
3.4.4.1. cfxExportNodeCount..................................................................................................... 51
3.4.4.2. cfxExportNodeList......................................................................................................... 51
3.4.4.3. cfxExportNodeGet......................................................................................................... 51
3.4.4.4. cfxExportNodeFree........................................................................................................ 51
3.4.5. Element Routines................................................................................................................... 51
3.4.5.1. cfxExportElementCount................................................................................................. 51
3.4.5.2. cfxExportElementList..................................................................................................... 52
3.4.5.3. cfxExportElementGet..................................................................................................... 52
3.4.5.4. cfxExportElementFree ................................................................................................... 53
3.4.6. Region Routines..................................................................................................................... 53
3.4.6.1. cfxExportRegionCount .................................................................................................. 53
3.4.6.2. cfxExportRegionSize...................................................................................................... 53
3.4.6.3. cfxExportRegionName................................................................................................... 53
3.4.6.4. cfxExportRegionList....................................................................................................... 53
3.4.6.5. cfxExportRegionGet ...................................................................................................... 54
3.4.6.6. cfxExportRegionFree ..................................................................................................... 54
3.4.7. Face Routines......................................................................................................................... 54
3.4.7.1. cfxExportFaceNodes...................................................................................................... 54
3.4.8.Volume Routines.................................................................................................................... 55
3.4.8.1. cfxExportVolumeCount.................................................................................................. 55
3.4.8.2. cfxExportVolumeSize..................................................................................................... 56
3.4.8.3. cfxExportVolumeName.................................................................................................. 56
3.4.8.4. cfxExportVolumeList...................................................................................................... 56
3.4.8.5. cfxExportVolumeGet ..................................................................................................... 56
3.4.8.6. cfxExportVolumeFree .................................................................................................... 56
3.4.9. Boundary Condition Routines................................................................................................. 56
3.4.9.1. cfxExportBoundaryCount .............................................................................................. 57
3.4.9.2. cfxExportBoundaryName............................................................................................... 57
3.4.9.3. cfxExportBoundaryType ................................................................................................ 57
3.4.9.4. cfxExportBoundarySize.................................................................................................. 57
3.4.9.5. cfxExportBoundaryList .................................................................................................. 57
3.4.9.6. cfxExportBoundaryGet .................................................................................................. 58
3.4.9.7. cfxExportBoundaryFree................................................................................................. 58
3.4.10.Variable Routines.................................................................................................................. 58
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3.4.10.1. cfxExportVariableCount............................................................................................... 58
3.4.10.2. cfxExportVariableSize .................................................................................................. 58
3.4.10.3. cfxExportVariableName ............................................................................................... 59
3.4.10.4. cfxExportVariableList................................................................................................... 59
3.4.10.5. cfxExportVariableGet................................................................................................... 59
3.4.10.6. cfxExportVariableFree.................................................................................................. 60
4. Remeshing Guide.................................................................................................................................. 61
4.1. User Defined Remeshing................................................................................................................. 62
4.1.1. Remeshing with Key-Frame Meshes........................................................................................ 63
4.1.2. Remeshing with Automatic Geometry Extraction.................................................................... 63
4.2. ICEM CFD Replay Remeshing........................................................................................................... 64
4.2.1. Steps to Set Up a Simulation Using ICEM CFD Replay Remeshing............................................. 66
4.3. Directory Structure and Files Used During Remeshing..................................................................... 67
4.4. Additional Considerations............................................................................................................... 68
4.4.1. Mesh Re-Initialization During Remeshing................................................................................ 68
4.4.2. Software License Handling..................................................................................................... 68
4.4.3. Results File Option................................................................................................................. 68
5. Reference Guide for Mesh Deformation and Fluid-Structure Interaction............................................ 69
5.1. Mesh Deformation.......................................................................................................................... 69
5.1.1. Mesh Folding: Negative Sector and Element Volumes.............................................................. 69
5.1.2. Applying Large Displacements Gradually................................................................................ 69
5.1.3. Consistency of Mesh Motion Specifications............................................................................. 70
5.1.4. Solving the Mesh Displacement Equations and Updating Mesh Coordinates........................... 70
5.1.5. Mesh Displacement Diffusion Scheme.................................................................................... 70
5.1.6. Mesh Displacement vs.Total Mesh Displacement.................................................................... 73
5.1.7. Simulation Restart Behavior.................................................................................................... 73
5.2. Fluid Structure Interaction.............................................................................................................. 74
5.2.1. Unidirectional (One-Way) FSI.................................................................................................. 74
5.2.1.1. Using CFX Only.............................................................................................................. 74
5.2.1.2. Using CFX and the Mechanical Application.................................................................... 74
5.2.1.2.1. Importing Data from the Mechanical Application Solver........................................ 74
5.2.1.2.2. Export Data to Other ANSYS Software Products..................................................... 75
5.2.1.2.3. Mechanical Import/Export Example: One-Way FSI Data Transfer............................. 75
5.2.1.3. Using CFX and Other CAE Software................................................................................ 75
5.2.2. Bidirectional (Two-Way) FSI.................................................................................................... 76
5.2.2.1. Using CFX Only.............................................................................................................. 76
5.2.2.2. Using CFX and the Mechanical Application.................................................................... 76
5.2.2.3. Using CFX and Other CAE Software................................................................................ 78
6. CFX Best Practices Guide for Numerical Accuracy................................................................................ 79
6.1. An Approach to Error Identification, Estimation and Validation......................................................... 79
6.2. Definition of Errors in CFD Simulations............................................................................................ 80
6.2.1. Numerical Errors .................................................................................................................... 81
6.2.1.1. Solution Errors............................................................................................................... 81
6.2.1.2. Spatial Discretization Errors........................................................................................... 82
6.2.1.3.Time Discretization Errors.............................................................................................. 82
6.2.1.4. Iteration Errors .............................................................................................................. 84
6.2.1.5. Round-off Error.............................................................................................................. 84
6.2.1.6. Solution Error Estimation............................................................................................... 84
6.2.2. Modeling Errors ..................................................................................................................... 87
6.2.3. User Errors............................................................................................................................. 88
6.2.4. Application Uncertainties....................................................................................................... 88
6.2.5. Software Errors ...................................................................................................................... 89
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6.3. General Best Practice Guidelines..................................................................................................... 89
6.3.1. Avoiding User Errors............................................................................................................... 89
6.3.2. Geometry Generation ............................................................................................................ 89
6.3.3. Grid Generation..................................................................................................................... 90
6.3.4. Model Selection and Application............................................................................................ 91
6.3.4.1.Turbulence Models........................................................................................................ 91
6.3.4.1.1. One-equation Models........................................................................................... 92
6.3.4.1.2.Two-equation Models........................................................................................... 93
6.3.4.1.3. Second Moment Closure (SMC) Models................................................................. 93
6.3.4.1.4. Large Eddy Simulation Models.............................................................................. 93
6.3.4.1.5.Wall Boundary Conditions..................................................................................... 94
6.3.4.1.5.1.Wall Function Boundary Conditions.............................................................. 94
6.3.4.1.5.2. Integration to the wall (low-Reynolds number formulation)........................... 95
6.3.4.1.5.3. Mixed formulation (automatic near-wall treatment)...................................... 95
6.3.4.1.5.4. Recommendations for Model Selection......................................................... 95
6.3.4.2. Heat Transfer Models..................................................................................................... 95
6.3.4.3. Multi-Phase Models....................................................................................................... 96
6.3.5. Reduction of Application Uncertainties................................................................................... 96
6.3.6. CFD Simulation...................................................................................................................... 97
6.3.6.1.Target Variables............................................................................................................. 97
6.3.6.2. Minimizing Iteration Errors............................................................................................. 97
6.3.6.3. Minimizing Spatial Discretization Errors......................................................................... 98
6.3.6.4. Minimizing Time Discretization Errors............................................................................ 98
6.3.6.5. Avoiding Round-Off Errors............................................................................................. 99
6.3.7. Handling Software Errors........................................................................................................ 99
6.4. Selection and Evaluation of Experimental Data.............................................................................. 100
6.4.1.Verification Experiments....................................................................................................... 100
6.4.1.1. Description.................................................................................................................. 100
6.4.1.2. Requirements.............................................................................................................. 100
6.4.2.Validation Experiments......................................................................................................... 101
6.4.2.1. Description.................................................................................................................. 101
6.4.2.2. Requirements.............................................................................................................. 101
6.4.3. Demonstration Experiments................................................................................................. 102
6.4.3.1. Description.................................................................................................................. 103
6.4.3.2. Requirements.............................................................................................................. 103
7. CFX Best Practices Guide for Cavitation.............................................................................................. 105
7.1. Liquid Pumps................................................................................................................................ 105
7.1.1. Pump Performance without Cavitation................................................................................. 105
7.1.2. Pump Performance with Cavitation....................................................................................... 106
7.1.3. Procedure for Plotting Performance Curve............................................................................ 107
7.1.4. Setup................................................................................................................................... 107
7.1.5. Convergence Tips................................................................................................................. 108
7.1.6. Post-Processing.................................................................................................................... 108
8. CFX Best Practices Guide for Combustion........................................................................................... 109
8.1. Gas Turbine Combustors............................................................................................................... 109
8.1.1. Setup................................................................................................................................... 109
8.1.1.1. Steady State vs.Transient............................................................................................. 109
8.1.1.2.Turbulence Model........................................................................................................ 109
8.1.1.3. Reference Pressure ...................................................................................................... 109
8.1.1.4. Combustion Model...................................................................................................... 109
8.1.2. Reactions............................................................................................................................. 110
8.1.3. Convergence Tips................................................................................................................. 110
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8.1.4. Post-Processing.................................................................................................................... 111
8.2. Combustion Modeling in HVAC Cases............................................................................................ 111
8.2.1. Set Up.................................................................................................................................. 111
8.2.2. Convergence Tips................................................................................................................. 112
8.2.3. Post-processing.................................................................................................................... 112
9. CFX Best Practices Guide for HVAC..................................................................................................... 113
9.1. HVAC Simulations......................................................................................................................... 113
9.1.1. Setting Up HVAC Simulations................................................................................................ 113
9.1.1.1. Buoyancy .................................................................................................................... 113
9.1.1.2.Thermal Radiation ....................................................................................................... 114
9.1.1.2.1.Thermal Radiation Model.................................................................................... 114
9.1.1.2.2. Spectral Model.................................................................................................... 114
9.1.1.2.3. Scattering Model ................................................................................................ 114
9.1.1.3. CHT (Conjugate Heat Transfer) Domains....................................................................... 115
9.1.1.4. Mesh Quality............................................................................................................... 115
9.1.1.5. Fans ............................................................................................................................ 116
9.1.1.6.Thermostats ................................................................................................................ 116
9.1.1.7. Collections of Objects.................................................................................................. 116
9.2. Convergence Tips ......................................................................................................................... 116
10. CFX Best Practices Guide for Multiphase.......................................................................................... 117
10.1. Bubble Columns ......................................................................................................................... 117
10.1.1. Setup................................................................................................................................. 117
10.1.2. Convergence Tips............................................................................................................... 118
10.1.3. Post-Processing.................................................................................................................. 118
10.2. Mixing Vessels............................................................................................................................. 118
10.2.1. Setup................................................................................................................................. 118
10.3. Free Surface Applications............................................................................................................ 119
10.3.1. Setup................................................................................................................................. 119
10.3.2. Convergence Tips............................................................................................................... 119
10.4. Multiphase Flow with Turbulence Dispersion Force...................................................................... 120
11. CFX Best Practices Guide for Turbomachinery.................................................................................. 121
11.1. Gas Compressors and Turbines.................................................................................................... 121
11.1.1. Setup for Simulations of Gas Compressors and Turbines...................................................... 121
11.1.2. Convergence Tips............................................................................................................... 122
11.1.3. Computing Speedlines for a Machine.................................................................................. 122
11.1.4. Post-Processing.................................................................................................................. 123
11.2. Liquid Pumps and Turbines......................................................................................................... 124
11.2.1. Setup for Simulations of Liquid Pumps and Turbines........................................................... 124
11.2.2. Convergence Tips............................................................................................................... 125
11.2.3. Post-Processing.................................................................................................................. 125
11.3. Fans and Blowers........................................................................................................................ 125
11.3.1. Setup for Simulations of Fans and Blowers.......................................................................... 125
11.3.2. Convergence Tips............................................................................................................... 125
11.3.3. Post-Processing.................................................................................................................. 126
11.4. Frame Change Models................................................................................................................. 126
11.4.1. Frozen Rotor....................................................................................................................... 126
11.4.2. Stage ................................................................................................................................. 127
11.4.3.Transient Rotor-Stator......................................................................................................... 127
11.5. Domain Interface Setup.............................................................................................................. 127
11.5.1. General Considerations ...................................................................................................... 127
11.5.2. Case 1: Impeller/Volute....................................................................................................... 128
11.5.3. Case 2: Step Change Between Rotor and Stator................................................................... 128
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Reference Guide
11.5.4. Case 3: Blade Passage at or Close to the Edge of a Domain................................................... 129
11.5.5. Case 4: Impeller Leakage..................................................................................................... 130
11.5.6. Case 5: Domain Interface Near Zone of Reversed Flow......................................................... 131
12. Best Practice: Scale-Resolving Simulations in ANSYS CFD............................................................... 133
12.1. Introduction ............................................................................................................................... 133
12.2. General Aspects.......................................................................................................................... 134
12.2.1. Limitations of Large Eddy Simulation (LES).......................................................................... 135
12.3. Scale-Resolving Simulation (SRS) Models – Basic Formulations..................................................... 144
12.3.1. Scale-Adaptive Simulation (SAS)......................................................................................... 145
12.3.2. Detached Eddy Simulation (DES)......................................................................................... 147
12.3.3. Large Eddy Simulation (LES)................................................................................................ 149
12.3.4.Wall Modeled Large Eddy Simulation (WMLES).................................................................... 149
12.3.5. Embedded/Zonal LES (ELES, ZLES)...................................................................................... 151
12.3.6. Unsteady Inlet/Interface Turbulence................................................................................... 152
12.4. Generic Flow Types and Basic Model Selection............................................................................. 153
12.4.1. Globally Unstable Flows...................................................................................................... 153
12.4.1.1. Flow Physics.............................................................................................................. 153
12.4.1.2. Modeling................................................................................................................... 154
12.4.1.3. Meshing Requirements.............................................................................................. 155
12.4.1.4. Numerical Settings .................................................................................................... 156
12.4.1.5. Examples................................................................................................................... 156
12.4.1.5.1. Flow around a Fighter Aircraft........................................................................... 156
12.4.1.5.2. Flow around a Triangular Cylinder...................................................................... 157
12.4.1.5.3. ITS Combustion Chamber.................................................................................. 159
12.4.2. Locally Unstable Flows........................................................................................................ 164
12.4.2.1. Flow Physics.............................................................................................................. 164
12.4.2.2. Modeling................................................................................................................... 165
12.4.2.3. Meshing Requirements.............................................................................................. 166
12.4.2.4. Numerical Settings .................................................................................................... 167
12.4.2.5. Examples................................................................................................................... 167
12.4.2.5.1. Backward-Facing Step I..................................................................................... 167
12.4.3. Stable Flows and Wall Boundary Layers............................................................................... 171
12.4.3.1. Flow Physics.............................................................................................................. 171
12.4.3.2. Modeling................................................................................................................... 172
12.4.3.3. Meshing Requirements.............................................................................................. 172
12.4.3.4. Numerical Settings .................................................................................................... 174
12.4.3.5. Examples................................................................................................................... 174
12.4.3.5.1. Periodic Channel............................................................................................... 174
12.4.3.5.2.Wall Boundary Layer.......................................................................................... 177
12.4.3.5.3. NASA Hump Flow.............................................................................................. 182
12.4.3.5.4.T-Junction with Thermal Mixing......................................................................... 184
12.5. Numerical Settings for SRS.......................................................................................................... 192
12.5.1. Spatial Discretization.......................................................................................................... 192
12.5.1.1. Momentum............................................................................................................... 192
12.5.1.2.Turbulence Equations................................................................................................ 194
12.5.1.3. Gradients (ANSYS Fluent)........................................................................................... 194
12.5.2. Pressure (ANSYS Fluent)...................................................................................................... 194
12.5.3.Time Discretization............................................................................................................. 194
12.5.3.1.Time Integration........................................................................................................ 194
12.5.3.2.Time Advancement and Under-Relaxation (ANSYS Fluent).......................................... 195
12.6. Initial and Boundary Conditions.................................................................................................. 195
12.6.1. Initialization of SRS............................................................................................................. 195
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