/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: v1606+ | | \\ / A nd | Web: www.OpenFOAM.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object snappyHexMeshDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // /*The utility snappyHexMesh (sHM) is to create "automatically" high quality 3D hex-dominant meshes from input of triangulated surfaces or simple primitive shapes. It was developed by Mattijs Janssens, Eugene de Villiers and Andre Jackson. Most of the time: surfaceFeatureExtract utility need to be run before sHM. */ // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // castellatedMesh true; /* detects the intersections between the surface object and the background grid. It can eventually refine the background grid at the vicinity of the object. Then it removes either the inside or the outside of the object. */ snap true; /*Introduces tetrahedral cells at the object boundary to match the actual geometry. */ addLayers false; /* true [false]: Add [do not add] layers to cells on the boundaries. */ /* Geometry. Definition of all surfaces. All surfaces are of class searchableSurface. Surfaces are used - to specify refinement for any mesh cell intersecting it - to specify refinement for any mesh cell inside/outside/near - to 'snap' the mesh boundary to the surface */ // STL, OBJ or NASTRAN surface files. Several objects may be inserted at the // same times. geometry { geom1.stl { type triSurfaceMesh; name zone1; //The solid boundaries will be named "zone1" } geom2.stl { type triSurfaceMesh; regions { inlet { name inlet; } outlet { name outlet; } walls { name walls; } } } geom3.stl { type distributedTriSurfaceMesh; distributionType follow; name zone3; /*Utility surfaceRedistributePar is used to initially decompose the surface. 3 distribution methods available "independent": distribution independent of mesh to produce best memory balance, "follow": distribution based on mesh bounding box to reduce communication "frozen": distribution remains unchanged */ } //- Refine a bit extra around the small centre hole: use of PRIMITIVE SHAPE refineHole { type searchableSphere; //Basic shapes: box, cylinder, sphere... centre (0 0 -0.0); radius 0.03; } refinementBox { type searchableBox; min (-1.0 -1.0 -1.0); max (1.0 1.0 1.0); } cylinder { type searchableCylinder; point1 (0 0 0); point2 (1 0 0); radius 0.1; } //User defined shapes: Complex shapes - Collection of basic shapes scaled //and transformed twoBoxes { type searchableSurfaceCollection; mergeSubRegions true; boxA { surface box; scale (1.0 1.0 2.1); transform { type cartesian; origin (2 2 0); e1 (1 0 0); e3 (0 0 1); } } boxB { surface box; scale (1.0 1.0 2.1); transform { type cartesian; origin (3.5 3 0); e1 (1 0 0); e3 (0 0 1); } } } }; /*Settings for the castellatedMesh generation: Cell splitting around the STL geometry. */ castellatedMeshControls { // Refinement parameters // ~~~~~~~~~~~~~~~~~~~~~ /*Surface refinement based on curvature of the input geometry Volume refinement (inside/outside/distance) based on primitive objects or additional imported geometry Edge refinement based on eMesh description */ /*If local number of cells is >= maxLocalCells on any processor switches from from refinement followed by balancing (current method) to (weighted) balancing before refinement. */ maxLocalCells 100000; /*Overall cell limit (approximately). Refinement will stop immediately upon reaching this number so a refinement level might not complete. Note that this is the number of cells before removing the part which isn't 'visible' from the keepPoint. Final number of cells might actually be a lot less. */ maxGlobalCells 2000000; /*The surface refinement loop might spend lots of iterations refining just a few cells. This setting will cause refinement to stop if <= minimumRefine are selected for refinement. Note: it will at least do one iteration (unless the number of cells to refine is 0) */ minRefinementCells 0; /*Number of buffer layers between different levels. 1 means normal 2:1 refinement restriction, larger means slower refinement. */ nCellsBetweenLevels 1; // Explicit feature edge refinement // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /*user-defined Features: Specifies a level for any cell intersected by its edges. This is a featureEdgeMesh, read from constant/triSurface for now.*/ features ( { file "flange.extendedFeatureEdgeMesh"; level 0; } { "bottomAir.eMesh"; level 1; } { file "heater.eMesh"; level ((0.01 2)); } { file "leftSolid.eMesh"; level 1; } ); // Surface based refinement // ~~~~~~~~~~~~~~~~~~~~~~~~ /*Specifies two levels for every surface. The first is the minimum level, every cell intersecting a surface gets refined up to the minimum level. Second level is the maximum level. Cells that 'see' multiple intersections where the intersections make an angle > resolveFeatureAngle get refined up to the maximum level. */ refinementSurfaces { flange { level (2 2); // Surface-wise min and max refinement level patchInfo { type wall; } } bottomAir { level (1 1); // Surface-wise min and max refinement level faceZone bottomAir; cellZone bottomAir; cellZoneInside inside; } } resolveFeatureAngle 30; // Region-wise refinement // ~~~~~~~~~~~~~~~~~~~~~~ /*Specifies refinement level for cells in relation to a surface. One of three modes - distance: 'levels' specifies per distance to the surface the wanted refinement level. The distances need to be specified in descending order. - inside: 'levels' is only one entry and only the level is used. All cells inside the surface get refined up to the level. The surface needs to be closed for this to be possible. - outside: Same but cells outside. */ refinementRegions { refineHole { mode inside; levels ((1E15 3)); } } // Mesh selection // ~~~~~~~~~~~~~~ /*After refinement patches get added for all refinementSurfaces and all cells intersecting the surfaces get put into these patches. The section reachable from the locationInMesh is kept. NOTE:This point should never be on a face, always inside a cell, even after refinement. */ locationInMesh (0 0.5 0.5); /* Inside point - Another explanation: Point a location where there is void space. All cells outside the void space will be removed. */ /*Whether any faceZones (as specified in the refinementSurfaces) are only on the boundary of corresponding cellZones or also allow free-standing zone faces. Not used if there are no faceZones. */ allowFreeStandingZoneFaces true; } // Settings for the snapping. snapControls { /*No. of patch smoothing itern before finding correspondence to surface */ nSmoothPatch 3; /*Relative distance for points to be attracted by surface feature point or edge. True distance is this factor times local maximum edge length. */ tolerance 1.0; /*Number of mesh displacement relaxation iterations. */ nSolveIter 300; /*Maximum number of snapping relaxation iterations. Should stop before upon reaching a correct mesh. */ nRelaxIter 5; /*Feature snapping: Number of feature edge snapping iterations. Leave out altogether to disable. */ nFeatureSnapIter 10; //- Detect (geometric) features by sampling the surface implicitFeatureSnap false; //- Use castellatedMeshControls::features explicitFeatureSnap true; //- Detect features between multiple surfaces (default = false) multiRegionFeatureSnap true; } //- Settings for the layer addition. addLayersControls { /*Are the thickness parameters below relative to the undistorted size of the refined cell outside layer (true) or absolute sizes (false). */ relativeSizes true; //Per final patch (so not geometry!) the layer information layers { "flange_.*" { //Note support for Regular Expression syntax nSurfaceLayers 1; //Number of layers to be grown on each patch } } // Expansion factor for layer mesh, relative growth rate expansionRatio 1.05; /*Wanted thickness of final added cell layer. If multiple layers is thickness of the layer furthest away from the wall. Relative to undistorted size of cell outside layer. See relativeSizes parameter. */ finalLayerThickness 0.3; /*Minimum thickness of cell layer. If for any reason layer cannot be above minThickness do not add layer. See relativeSizes parameter. */ minThickness 0.25; /*If points get not extruded do nGrow layers of connected faces that are also not grown. This helps convergence of the layer addition process close to features. */ nGrow 0; //Advanced settings //When not do extrude surface. 0 is flat surface, 90 is when two faces are //perpendicular. Layers above featureAngle are collapsed automatically. featureAngle 30; //Maximum number of snapping relaxation iterations. Should stop before upon //reaching a correct mesh. nRelaxIter 5; //Number of smoothing iterations of surface normals nSmoothSurfaceNormals 1; //Number of smoothing iterations of interior mesh movement direction nSmoothNormals 3; //Smooth layer thickness over surface patches nSmoothThickness 10; //Stop layer growth on highly warped cells maxFaceThicknessRatio 0.5; //Reduce layer growth where ratio thickness to medial distance is large maxThicknessToMedialRatio 0.3; //Angle used to pick up medial axis points minMedianAxisAngle 90; //Create buffer region for new layer terminations nBufferCellsNoExtrude 0; /*Overall max number of layer addition iterations. The mesher will exit if it reaches this number of iterations; possibly with an illegal mesh. */ nLayerIter 50; /*Max number of iterations after which relaxed meshQuality controls get used. Up to nRelaxIter it uses the settings in meshQualityControls, after nRelaxIter it uses the values in meshQualityControls::relaxed. */ nRelaxedIter 20; } /*Generic mesh quality settings. At any undoable phase these determine where to undo. */ meshQualityControls { #include "meshQualityDict" // Optional : some meshing phases allow usage of relaxed rules. // See e.g. addLayersControls::nRelaxedIter. relaxed { maxNonOrtho 75; //Maximum non-orthogonality allowed. Set to 180 to disable. } // Advanced //- Number of error distribution iterations nSmoothScale 4; //- Amount to scale back displacement at error points errorReduction 0.75; } //Advanced //Write flags writeFlags ( scalarLevels // write volScalarField with cellLevel for postprocessing layerSets // write cellSets, faceSets of faces in layer layerFields // write volScalarField for layer coverage ); //Merge tolerance. Is fraction of overall bounding box of initial mesh. //Note: the write tolerance needs to be higher than this. mergeTolerance 1E-6; // ************************************************************************* //