ICEM 原版培训教程(ANSYS 公司提供)7

Chapter4Chapter4VolumeMeshingICEMCFDIntroductoryCourse4-1ANSYS,Inc.Proprietary©2009ANSYS,Inc.Allrightsreserved.July2009Inventory#002663VolumeMeshingTrainingManualIntroductiontovolumemeshing•Toautomaticallycreate3Delementstofillvolumetricdomain–Generallytermed“unstructured”•MainlytetraMainlytetra–Full3Danalysis•Where2Dapproximationsdon’ttellthefullstory–Internal/ExternalflowsimulationInternal/Externalflowsimulation–Structuralsolidmodeling–Thermalstress–Manymore!•Standardprocedures–Startfromjustgeometry•Octreetetra–Robust–Startfromexistingshellmesh•Delauney/T-grid–Quick–Bothgeometryandshellmesh•Portionsofmodelobust–Walkoverfeatures•Cartesian–Fastest•Havetosetsizes–Quick•AdvancingFront–Smoothergradients,sizetransition•HexCorealreadymeshed–Inflationlayers•“Prism”4-2ANSYS,Inc.Proprietary©2009ANSYS,Inc.Allrightsreserved.July2009Inventory#002663Havetosetsizes•HexCore•HexDominantVolumeMeshingTrainingManualGeneralProcedure•Firstdecidevolumemeshparameters•Firstdecidevolumemeshparameters–GlobalMeshSetupVolumeMeshingParameters–SelectMeshTypeSelectMeshMethodforselectedType•Load/createsurfacemesh–AsinShellMeshingchapter–SelectMeshMethodforselectedType–SetoptionsforspecificMethods•Setmeshsizes–Globally•AsinShellMeshing–ForDelauney,AdvancingFront,T-grid,Hex-Dominant•Eitherofthesetypesrunfromgeometrywill•AsinShellMeshing–Locally•Part/Surface/CurveMeshSetup•AsinShellMeshing•ForFromgeometryonlyfromgeometrywillautomaticallycreatesurfacemeshusingglobalandlocalShellMeshsettingswithoutanyuserinput/editing–Octree–Cartesian•Definevolumetricregion–TypicallyforoctreeoncomplexmodelsMltill•Ifindoubt,runShellMeshfirst,thenfromexistingmesh•ComputeMeshMhCtMh•ComputePrism(optional)–Asseparateprocess–Multiplevolumes•Definedensityregions(optional)•Applyingmeshsizewithinvolumewheregeometrydoesn’texist–MeshComputeMeshVolumeMesh4-3ANSYS,Inc.Proprietary©2009ANSYS,Inc.Allrightsreserved.July2009Inventory#002663–AlsooptiontorunautomaticallyfollowingtetracreationVolumeMeshingTrainingManualBody/MaterialPoint•DefineVolumetricDomainOptional–Optional•Recommendedforcomplexgeometries•Multiplevolumes–Geometry-CreateBody–MaterialPoint•Centroidof2points–Selectanytwolocationswhosemid-pointiswithinvolume–Preferred•Atspecifiedpoint–Definevolumeregionby“point”withinvolume–ByTopology•Definesvolumeregionbysetofclosedsurfacesgy•MustfirstBuildDiagnosticTopology•Entiremodel–AutomaticallydefineallvolumesSelectedsurfaces4-4ANSYS,Inc.Proprietary©2009ANSYS,Inc.Allrightsreserved.July2009Inventory#002663•Selectedsurfaces–UserselectssurfacesthatformaclosedvolumeVolumeMeshingTrainingManualMeshTypes•Tetra/mixed–Mostused–TetraPuretetra–Withhexcore•Hexa(cartesian)fillingmajorityvolume•Tetra(fromdelauneyalgorithm)used(yg)tofillbetweensurfaceortopofinflationlayersandhexcore•PyramidstomakeconformalbetweentetratriandhexquadfacesTetra/Prismq–Withinflationlayers•Prismsfromtrisurfacemesh•Hexasfromquadsurfacemesh•Tetraand/orhexcorefillinginterior•Pyramidstocapoffanyquadfaces–OfhexcoreorhexinflationlayersMergedhybridwithstructuredhexTetra/Prism/Hexcore4-5ANSYS,Inc.Proprietary©2009ANSYS,Inc.Allrightsreserved.July2009Inventory#002663–MergedhybridwithstructuredhexmeshVolumeMeshingTrainingManualMeshTypes•Hexa-Dominant–FromexistingquadmeshGoodqualityhexnearsurface–Goodqualityhexnearsurface–Somewhatpoorininterior–Typicallygoodenoughforstaticdisplacementstaticdisplacement–Notcoveredindetailhere•Cartesian–Automaticpurehexa–Rectilinearmesh–Staircaseor–Bodyfitted–Fastestmethodforcreatingvolumemesh4-6ANSYS,Inc.Proprietary©2009ANSYS,Inc.Allrightsreserved.July2009Inventory#002663–NotcoveredindetailhereVolumeMeshingTrainingManualMeshMethod•Tetra/Mixed–Robust(Octree)•SameasShellMeshingPatchIndependentSameasShellMeshingPatchIndependent–Retainsvolumetrictetras•Ifyouhavecomplexand/ordirtygeometry•Don’twanttospendtoomuchtimewithgeometrycleanup•Don’twanttospendtoomuchtimewithdetailedshellmeshing•Don’twanttospendtimedefeaturinggeometryDontwanttospendtimedefeaturinggeometry•Justsetappropriatemeshsizesongeometry–Parts–Surfaces–Curves–ReviewShellMeshingchapter•Part/Surface/CurveMeshSetup4-7ANSYS,Inc.Proprietary©2009ANSYS,Inc.Allrightsreserved.July2009Inventory#002663VolumeMeshingTrainingManualOctreeMethod•ICEMTetrausespatch-independentOctreemethod–Volumefirstgeneratedindependentofsurfacemodel–Nodesareprojectedtomodelsurfaces,curvesandpointsMeshdetail–Surfacemeshiscreated•ResultingmeshisindependentoftheunderlyingarrangementofsurfacesNotallsurfaceedgesneedtobecaptured!–Notallsurfaceedgesneedtobecaptured!–Makecurves/pointsdormant•Delete•Filterpoints/curvesunderBuildDiagnosticTopologyGeometryMeshSliverignored4-8ANSYS,Inc.Proprietary©2009ANSYS,Inc.Allrightsreserved.July2009Inventory#002663MeshVolumeMeshingTrainingManualGeometryRequirementsforOctreeTetra•Tetrarequiresanenclosedsurfacemodel–RunBuildDiagnosticTopologyGeometryRepairtoolsquicklylocatetofindgaps/holes–Octreecantolerategapssmallerthenthelocalelementsizetoolsquicklylocateandfixtheseproblems.size•RecommendpointsandcurvesatkeyfeaturesRecommendMaterial