Geometry modeling and grid generation

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1、GridGeneration•Geometrydefinition(simpleshapes,CADimport)•Gridgenerationalgorithms•GAMBIT•Gridqualityandimprovement•AutomationME469B/2/GI1Gridgenerationpackage:GAMBITSpecialGeometryGridBCToolsGeometryToolsGraphicsWindowVolumeToolsVisualizationTextToolsWindowTheUserManualisavailablefromthe

2、classWebSiteME469B/2/GI21Geometricaltypes-Topology•Vertex•Edge(2ormorevertices)•Face(3ormoreedges)•Volume(3ormorefaces)Bottom-upapproach:generatelowdimensionalentitiesandbuildontopofthemhigherdimensionalentitiesME469B/2/GI3Vertex:•InputCoordinates…Edge:•Linesegment(connect2vertices)•Circu

3、lararc•Quadraticfunctions•NURBS:Non-UniformRationalB-Splines(connectNvertices)TopologicallyanyedgeisALWAYSaconnectionbetween2vertices(additionalverticesusedtobuildthegeometryareNOTpartoftheedge)ME469B/2/GI42Face:•Rectangular•Circular•…•Sweep(translationorrotationofanedge)•Wireframe(connec

4、ting3ormoreedges)ME469B/2/GI5Volume:•Cuboid•Sphere•Cone•Pyramids•…•Sweep(translationorrotationofaface)•Wireframe(connecting3ormorefaces)ME469B/2/GI63ManipulateGeometry-BooleanOperations:Volume1•Unite•Substract•IntersectVolume2itgeneratestheintersectionedgeME469B/2/GI7ManipulateGeometry-Bl

5、endsmoothsharpedgesME469B/2/GI84CreateEntities-FacesME469B/2/GI9CreateEntities-FacesSomeentitiesgeneratedusing“primitives”havefewerlowertopologicalentitiesExample:Cubevolume:6faces,12edges,8verticesCylindervolume:3faces,2edges,2verticesME469B/2/GI105ManipulateGeometry–CreateEntitiesCreate

6、avertexonafaceParametricrepresentationofthefaceME469B/2/GI11ManipulateGeometry–CreateEntitiesCreatetwoedgesbysplittinganedgeParametricrepresentationoftheedgeME469B/2/GI126ImportGeometries•RealisticgeometriesareTOOcomplicatedtobegeneratedfrom“simple”shapes•EngineeringdesignisbasedonCADsyst

7、emsTranslationbetweenCADandCFDsystemisamajorbottleneck•GambitisbasedonACISgeometricallibraries•ACIS(Andy,Charles&Ian’sSystem)isthemostwidelyused3Dmodelingsoftwaretechnology(http://www.spatial.com)•Itcanalsoimport:•STEP(STandardforExchangeofProductmodeldata;ISOstanda