Introduction to ansys meshing chapter 05

Chapter5Chapter5TetrahedralMeshwithInflationInflationIntroductiontoANSYSIntroductiontoANSYSMeshing5-1ANSYS,Inc.Proprietary©2010ANSYS,Inc.Allrightsreserved.Release12.0March2010TetrahedralMeshwithInflationTrainingManualOverview•TetrahedralMeshingAlgorithms•InflationOptionsforPatchConformingpg–Algorithms–PreandPost–AdvancedOptionsp–CollisionAvoidance•PatchIndependentMeshing–DefeaturingDefeaturing–Proximityrefinement–Curvaturerefinement•Workshop51TetrahedralMeshwithInflationforaTeeMixerWorkshop5.1TetrahedralMeshwithInflationforaTeeMixer(PatchConforming)•Workshop5.2FluidandStructuralMeshesforanAutoManifold(PatchIndependent)5-2ANSYS,Inc.Proprietary©2010ANSYS,Inc.Allrightsreserved.Release12.0March2010(PatchIndependent)TetrahedralMeshwithInflationTrainingManualTetrahedralMeshingAlgorithms•PatchConforming–Allfacesandedgesarerespectedbydefault(althoughthiscanbechangedwithpinchcontrolsandvirtualtopologyandthereisdefaultgppgydefeaturingbasedontheminimumsizelimit)–FormoderatelycleanCAD(i.e.nativeCAD,Parasolid,ACIS,Etc.)–Possibletocombinewithsweepsinamultibody-parttogenerateconformalhbidtt/idhhhybridtet/prismandhexmeshes–Workswithadvancedsizefunctions–SurfacemeshVolumemesh•PatchIndependent–UsefulforCADwithsliverfaces,manysurfacepatches,shortedges,etc.Biltidfti/ilifitibdhithl–Builtindefeaturing/simplificationbasedonmeshingtechnology–BasedonICEMCFDTetra/PrismOctreemethod–VolumemeshSurfacemesh5-3ANSYS,Inc.Proprietary©2010ANSYS,Inc.Allrightsreserved.Release12.0March2010TetrahedralMeshwithInflationTrainingManualInflationforPatchConformingTetrahedrons•BasicsettingsincludeInflationOptionaswellasPreandPostInflationAlgorithms5-4ANSYS,Inc.Proprietary©2010ANSYS,Inc.Allrightsreserved.Release12.0March2010TetrahedralMeshwithInflationTrainingManualInlationOption–SmoothTransition•SmoothTransition(Default)–Usesthelocaltetrahedralelementsizetocomputeeachlocalinitialheightandtotalheightsothattherateofvolumechangeissmooth.Eachtrianglethatisgggbeinginflatedwillhaveaninitialheightthatiscomputedwithrespecttoitsarea,averagedatthenodes.Thismeansthatforauniformmesh,theinitialheightswillberoughlythesame,whileforavaryingmesh,theinitialheightswillvary.TitiRti–TransitionRatio•Volume-basedsizechangebetweenthelastlayerofelementsintheinflationlayerandthefirstelementsinthetetrahedronregion.•WhentheSolverissettoCFX,thedefaultforTransitionRatiois0.77.Forallother,physicspreferences,includingCFDwhenSolverPreferenceissettoFluent,thedefaultis0.272.•ThedifferenceintreatmentarisesbecausetheFluentsolveriscell-centeredsothatthemeshelementisequaltothesolverelementwhiletheCFXsolverisvertex-themeshelementisequaltothesolverelement,whiletheCFXsolverisvertexcenteredwiththesolverelementconstructedfromthemeshdualsaboutanode.5-5ANSYS,Inc.Proprietary©2010ANSYS,Inc.Allrightsreserved.Release12.0March2010TetrahedralMeshwithInflationTrainingManualInflationOption–ThicknessOptions•TotalThickness–CreatesconstantinflationlayersusingthevaluesoftheNumberofLayersandygyGrowthRatecontrolstoobtainatotalthicknessasdefinedbythevalueoftheMaximumThicknesscontrol.UnlikeinflationwiththeSmoothTransitionoption,withtheTotalThicknessoptionthethicknessofthefirstinflationlayerandeachfollowinglayerisconstantandeachfollowinglayerisconstant•FirstLayerThickness–createsconstantinflationlayersusingthevaluesoftheFirstLayerHeight,MaximumLayersandGrowthRatecontrolstogeneratetheinflationmeshMaximumLayers,andGrowthRatecontrolstogeneratetheinflationmesh.UnlikeinflationwiththeSmoothTransitionoption,withtheFirstLayerThicknessoptionthethicknessofthefirstinflationlayerandeachfollowinglayerisconstant.5-6ANSYS,Inc.Proprietary©2010ANSYS,Inc.Allrightsreserved.Release12.0March2010TetrahedralMeshwithInflationTrainingManualInflationAlgorithms•Pre–TGridalgorithm–Defaultsettingforallphysicstype.ThesurfacemeshwillbeinflatedDefaultsettingforallphysicstype.Thesurfacemeshwillbeinflatedfirst,andthentherestofthevolumemeshwillbegenerated.–Doesnotsupportdifferentnumberoflayersonadjacentfaces.–AlsoapplicabletoSweepand2Dmeshing.pppg•Post–ICEMCFDalgorithm–ApostprocessingtechniquethatworksafterthetetrahedralmeshisApostprocessingtechniquethatworksafterthetetrahedralmeshisgeneratedisused.Validonlyforpatchingconformingandpatchindependenttetrahedrons.5-7ANSYS,Inc.Proprietary©2010ANSYS,Inc.Allrightsreserved.Release12.0March2010TetrahedralMeshwithInflationTrainingManualAdvancedInflationOptions•VisibleifViewAdvancedOptionsundertheGlobalInflationOptionsunderMeshissettoYes–CollisonAvoidance•LayerCompression(DefaultforFluent)•StairStepping(DefaultforCFX)GthRtT–GrowthRateType–MaximumAngle–FilletRatioUPtSthi–UsePostSmoothing–SmoothingIterations5-8ANSYS,Inc.Proprietary©2010ANSYS,Inc.Allrightsreserved.Release12.0March2010TetrahedralMeshwithInflationTrainingManualCollisionAvoidance•LayerCompression–Ifadvancinginflatedfrontsfromdifferentfacesareabouttocollide,theinflationlayersarecompressedinordertoleavelayersarecompressedinordertoleaveenoughroomforalayeroftets–Iflayercompressioncannotresolvecollision,layersmayberemovedasinstairsteppingdescribedbelow.