Fluent Newsletter Summer 2005

PRODUCT NEWSTGrid 4.0:Soon to be All Wrapped UpBy Erling Eklund, TGrid Product ManagerFluent WorldwideCorporate HeadquartersFluent Inc.10 Cavendish CourtLebanon, NH 03766, USATel: 603 643 2600800 445 4454Fax: 603 643 3967Email: info@fluent.comAn STL representation of aViking Ship; in the backgroundbelow, the initial Cartesian meshused for the wrapping procedureFOR COMPLEX INDUSTRIAL SIMULATIONSinvolving multiple geometry parts, such as automotiveengine analysis, mesh generation can beextremely challenging. Often, the original geometryis only available in discrete or “faceted” form, as inSTL, WRML, and D3S formats, for example. In additionto the complexity of the configuration, defectsare usually present, such as discontinuous surfaces,cracks, and overlaps, and unnecessary features canbe present as well. Conventional geometry-basedrepair (or cleanup, required for generating a watertightgeometry prior to meshing) is very tedious andcan consume the majority of the time and budgetallocated for the project.Surface WrappingThe new surface wrapping technology in TGrid4.0 allows the user to start from a very “dirty”geometry, and in the end, produce a fully connectedCFD surface mesh. In principal, it is basedon capturing a roughly defined volumetric regionusing a Cartesian grid. The grid is then intersectedwith the underlying geometry to form a shell,which is then projected back onto all faces of thegeometry. Throughout the process, individual featurescan be selectively captured and certainzones can be preserved.40 Fluent News · Summer 2005The finished surfacemesh on the shipand volume mesh inthe surroundingsThe surface wrapping operation is divided into fivedifferent sub-tasks: initialization, wrapping, featureselection and control, improvement, and zone separation.Prior to the initialization process, the minimumand maximum sizes of the initial Cartesian gridare specified. During initialization, all volumetricshells are created and the selected region can beinspected using several tools (panning and zoomingor face tracing, for example) to ensure that there areno unwanted leaks. Fixed-, curvature- and proximitybasedsize functions can be used to redistribute theinitial grid. Following initialization, the wrapper surfaceis created with a simple click of a button. Featurelines can be manually or automatically created andthe wrapper surface can be imprinted onto a selectedset of these features. The raw wrapper surface usuallycontains several problematic areas (such as selfintersection,folding, cross-over cells, or highly skewcells), which can be automatically and sequentiallyresolved using a single improvement operation.Before all zone names in the original model are recoveredduring the zone separation process, the user candisplay the local deviation between the original andwrapped surfaces.Around the WrapperSeveral tools – some new, some improved – are availableto help with pre- and post-wrapping operations.The selection helper can now be used to remove smallparts (like bolts and nuts) and it can also quickly identifyduplicate objects. All boundary modification toolsare available through shortcuts and this allows highendusers to quickly remove details and close holes inthe model. Meshed planes and boxes can be createdand used for patching and outer domain creation.Faces can be separated in a local manner for cleanup,re-meshing, or deletion. Face-face intersection hasbeen dramatically improved, enabling intersections offaces of largely different size, within a tolerant distance,and/or partially overlapping.Prism layersThere are several enhancements related to the creationof prism layers in TGrid 4.0. A prism proximity/collisiondetection capability with automaticheight adjustment has been added. Similarly, TGridis now equipped with automatic sharp-corner prismlayer handling, where prism layers can be locallypeeled off. These new capabilities, in combinationwith non-conformal quad-split and/or prism-sideremeshing, make TGrid 4.0 one of the market’s topqualityhybrid meshing tools. 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Ltd.Pune, IndiaTel: 91 20 2293770Email: info@fluent.co.inDistributorsAnova Ltd. – TurkeyATES – KoreaBeijing Hi-key Technology Corporation Ltd. –ChinaCavendish Instruments de Mexico, S.A. deC.V.(CIM) – Mexico, Venezuela, Argentina,Chile, ColombiaFEM++ – Israel (POLYFLOW only)Flowmen Technology Co., Ltd. – TaiwanFluid Codes Ltd. – UK (serving the Middle East)Fluvius Pty. Ltd. – Australia & New ZealandINNOTECH Ltd. – HungaryJ-ROM Ltd. – IsraelPlasmaVenture Ltd. – Russia & CISProcess Flow – Finland & BalticsQfinsoft – South AfricaRegional Technologies Corp. – UkraineSimTec Ltd. – Greece (serving Southeastern Europe)SMARTtech Services & Systems, Ltd. – BrazilSymKom – PolandTechsoft Engineering s.r.o. – Czech Republic &Slovak RepublicTENSOR srl – Romania