372 lines
11 KiB
C++
372 lines
11 KiB
C++
/*--------------------------------*- C++ -*----------------------------------*\
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| ========= | |
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| \\ / F ield | foam-extend: Open Source CFD |
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| \\ / O peration | Version: 4.0 |
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| \\ / A nd | Web: http://www.foam-extend.org |
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| \\/ M anipulation | |
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\*---------------------------------------------------------------------------*/
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FoamFile
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{
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version 2.0;
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format ascii;
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class dictionary;
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object snappyHexMeshDict;
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}
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// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
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// Which of the steps to run
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castellatedMesh true;
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snap true;
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addLayers false;
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// Geometry. Definition of all surfaces. All surfaces are of class
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// searchableSurface.
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// Surfaces are used
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// - to specify refinement for any mesh cell intersecting it
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// - to specify refinement for any mesh cell inside/outside/near
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// - to 'snap' the mesh boundary to the surface
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geometry
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{
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box1x1x1
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{
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type searchableBox;
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min (1.5 1 -0.5);
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max (3.5 2 0.5);
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}
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sphere.stl
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{
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type triSurfaceMesh;
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//tolerance 1E-5; // optional:non-default tolerance on intersections
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//maxTreeDepth 10; // optional:depth of octree. Decrease only in case
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// of memory limitations.
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// Per region the patchname. If not provided will be <name>_<region>.
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regions
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{
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secondSolid
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{
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name mySecondPatch;
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}
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}
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}
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sphere2
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{
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type searchableSphere;
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centre (1.5 1.5 1.5);
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radius 1.03;
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}
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};
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// Settings for the castellatedMesh generation.
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castellatedMeshControls
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{
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// Refinement parameters
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// ~~~~~~~~~~~~~~~~~~~~~
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// If local number of cells is >= maxLocalCells on any processor
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// switches from from refinement followed by balancing
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// (current method) to (weighted) balancing before refinement.
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maxLocalCells 100000;
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// Overall cell limit (approximately). Refinement will stop immediately
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// upon reaching this number so a refinement level might not complete.
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// Note that this is the number of cells before removing the part which
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// is not 'visible' from the keepPoint. The final number of cells might
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// actually be a lot less.
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maxGlobalCells 2000000;
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// The surface refinement loop might spend lots of iterations refining just a
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// few cells. This setting will cause refinement to stop if <= minimumRefine
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// are selected for refinement. Note: it will at least do one iteration
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// (unless the number of cells to refine is 0)
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minRefinementCells 0;
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// Allow a certain level of imbalance during refining
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// (since balancing is quite expensive)
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// Expressed as fraction of perfect balance (= overall number of cells /
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// nProcs). 0=balance always.
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maxLoadUnbalance 0.10;
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// Number of buffer layers between different levels.
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// 1 means normal 2:1 refinement restriction, larger means slower
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// refinement.
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nCellsBetweenLevels 1;
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// Explicit feature edge refinement
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// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// Specifies a level for any cell intersected by its edges.
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// This is a featureEdgeMesh, read from constant/triSurface for now.
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features
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(
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//{
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// file "someLine.eMesh";
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// level 2;
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//}
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);
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// Surface based refinement
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// ~~~~~~~~~~~~~~~~~~~~~~~~
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// Specifies two levels for every surface. The first is the minimum level,
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// every cell intersecting a surface gets refined up to the minimum level.
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// The second level is the maximum level. Cells that 'see' multiple
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// intersections where the intersections make an
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// angle > resolveFeatureAngle get refined up to the maximum level.
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refinementSurfaces
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{
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sphere.stl
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{
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// Surface-wise min and max refinement level
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level (2 2);
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// Optional region-wise level specification
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regions
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{
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secondSolid
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{
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level (3 3);
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}
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}
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// Optional angle to detect small-large cell situation perpendicular
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// to the surface. Is the angle of face w.r.t the local surface
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// normal. Use on flat(ish) surfaces only. Otherwise
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// leave out or set to negative number.
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//perpendicularAngle 10;
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}
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}
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resolveFeatureAngle 30;
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// Region-wise refinement
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// ~~~~~~~~~~~~~~~~~~~~~~
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// Specifies refinement level for cells in relation to a surface. One of
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// three modes
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// - distance. 'levels' specifies per distance to the surface the
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// wanted refinement level. The distances need to be specified in
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// descending order.
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// - inside. 'levels' is only one entry and only the level is used. All
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// cells inside the surface get refined up to the level. The surface
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// needs to be closed for this to be possible.
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// - outside. Same but cells outside.
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refinementRegions
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{
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box1x1x1
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{
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mode inside;
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levels ((1.0 4));
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}
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//sphere.stl
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//{
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// mode distance;
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// levels ((1.0 5) (2.0 3));
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//}
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}
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// Mesh selection
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// ~~~~~~~~~~~~~~
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// After refinement patches get added for all refinementSurfaces and
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// all cells intersecting the surfaces get put into these patches. The
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// section reachable from the locationInMesh is kept.
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// NOTE: This point should never be on a face, always inside a cell, even
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// after refinement.
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locationInMesh (5 0.28 0.43);
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// Whether any faceZones (as specified in the refinementSurfaces)
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// are only on the boundary of corresponding cellZones or also allow
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// free-standing zone faces
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allowFreeStandingZoneFaces true;
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}
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// Settings for the snapping.
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snapControls
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{
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//- Number of patch smoothing iterations before finding correspondence
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// to surface
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nSmoothPatch 3;
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//- Relative distance for points to be attracted by surface feature point
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// or edge. True distance is this factor times local
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// maximum edge length.
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tolerance 4.0;
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//- Number of mesh displacement relaxation iterations.
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nSolveIter 30;
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//- Maximum number of snapping relaxation iterations. Should stop
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// before upon reaching a correct mesh.
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nRelaxIter 5;
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}
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// Settings for the layer addition.
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addLayersControls
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{
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// Are the thickness parameters below relative to the undistorted
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// size of the refined cell outside layer (true) or absolute sizes (false).
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relativeSizes true;
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// Per final patch (so not geometry!) the layer information
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layers
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{
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sphere.stl_firstSolid
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{
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nSurfaceLayers 1;
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}
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maxY
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{
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nSurfaceLayers 1;
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}
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}
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// Expansion factor for layer mesh
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expansionRatio 1.0;
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//- Wanted thickness of final added cell layer. If multiple layers
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// is the thickness of the layer furthest away from the wall.
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// See relativeSizes parameter.
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finalLayerThickness 0.3;
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//- Minimum thickness of cell layer. If for any reason layer
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// cannot be above minThickness do not add layer.
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// See relativeSizes parameter.
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minThickness 0.25;
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//- If points get not extruded do nGrow layers of connected faces that are
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// also not grown. This helps convergence of the layer addition process
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// close to features.
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nGrow 1;
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// Advanced settings
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//- When not to extrude surface. 0 is flat surface, 90 is when two faces
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// make straight angle.
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featureAngle 60;
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//- Maximum number of snapping relaxation iterations. Should stop
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// before upon reaching a correct mesh.
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nRelaxIter 5;
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// Number of smoothing iterations of surface normals
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nSmoothSurfaceNormals 1;
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// Number of smoothing iterations of interior mesh movement direction
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nSmoothNormals 3;
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// Smooth layer thickness over surface patches
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nSmoothThickness 10;
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// Stop layer growth on highly warped cells
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maxFaceThicknessRatio 0.5;
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// Reduce layer growth where ratio thickness to medial
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// distance is large
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maxThicknessToMedialRatio 0.3;
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// Angle used to pick up medial axis points
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minMedianAxisAngle 130;
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// Create buffer region for new layer terminations
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nBufferCellsNoExtrude 0;
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// Overall max number of layer addition iterations. The mesher will exit
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// if it reaches this number of iterations; possibly with an illegal
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// mesh.
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nLayerIter 50;
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// Max number of iterations after which relaxed meshQuality controls
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// get used. Up to nRelaxIter it uses the settings in meshQualityControls,
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// after nRelaxIter it uses the values in meshQualityControls::relaxed.
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nRelaxedIter 20;
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}
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// Generic mesh quality settings. At any undoable phase these determine
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// where to undo.
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meshQualityControls
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{
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//- Maximum non-orthogonality allowed. Set to 180 to disable.
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maxNonOrtho 65;
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//- Max skewness allowed. Set to <0 to disable.
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maxBoundarySkewness 20;
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maxInternalSkewness 4;
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//- Max concaveness allowed. Is angle (in degrees) below which concavity
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// is allowed. 0 is straight face, <0 would be convex face.
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// Set to 180 to disable.
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maxConcave 80;
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//- Minimum projected area v.s. actual area. Set to -1 to disable.
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minFlatness 0.5;
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//- Minimum pyramid volume. Is absolute volume of cell pyramid.
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// Set to a sensible fraction of the smallest cell volume expected.
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// Set to very negative number (e.g. -1E30) to disable.
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minVol 1e-13;
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//- Minimum face area. Set to <0 to disable.
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minArea -1;
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//- Minimum face twist. Set to <-1 to disable. dot product of face normal
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//- and face centre triangles normal
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minTwist 0.05;
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//- minimum normalised cell determinant
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//- 1 = hex, <= 0 = folded or flattened illegal cell
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minDeterminant 0.001;
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//- minFaceWeight (0 -> 0.5)
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minFaceWeight 0.05;
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//- minVolRatio (0 -> 1)
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minVolRatio 0.01;
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//must be >0 for Fluent compatibility
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minTriangleTwist -1;
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//- if >0 : preserve single cells with all points on the surface if the
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// resulting volume after snapping (by approximation) is larger than
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// minVolCollapseRatio times old volume (i.e. not collapsed to flat cell).
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// If <0 : delete always.
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//minVolCollapseRatio 0.5;
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// Advanced
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//- Number of error distribution iterations
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nSmoothScale 4;
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//- amount to scale back displacement at error points
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errorReduction 0.75;
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// Optional : some meshing phases allow usage of relaxed rules.
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// See e.g. addLayersControls::nRelaxedIter.
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relaxed
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{
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//- Maximum non-orthogonality allowed. Set to 180 to disable.
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maxNonOrtho 75;
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}
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}
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// Advanced
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// Flags for optional output
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// 0 : only write final meshes
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// 1 : write intermediate meshes
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// 2 : write volScalarField with cellLevel for postprocessing
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// 4 : write current intersections as .obj files
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debug 0;
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// Merge tolerance. Is fraction of overall bounding box of initial mesh.
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// Note: the write tolerance needs to be higher than this.
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mergeTolerance 1E-6;
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// ************************************************************************* //
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