525 lines
17 KiB
C++
525 lines
17 KiB
C++
/*--------------------------------*- C++ -*----------------------------------*\
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| ========= | |
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| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
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| \\ / O peration | Version: dev |
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| \\ / A nd | Web: www.OpenFOAM.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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//Optional: single region surfaces get patch names according to
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// surface only. Multi-region surfaces get patch name
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// surface "_ "region. Default is true
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//singleRegionName 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 <surface>_<region>.
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// Note: this name cannot be used to identity this region in any
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// other part of this dictionary; it is only a name
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// for the combination of surface+region (which is only used
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// when creating patches)
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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 explicitly provided
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// edges.
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// This is a featureEdgeMesh, read from constant/triSurface for now.
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// Specify 'levels' in the same way as the 'distance' mode in the
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// refinementRegions (see below). The old specification
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// level 2;
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// is equivalent to
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// levels ((0 2));
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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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// levels ((0.0 2) (1.0 3));
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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 specification of patch type (default is wall). No
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// constraint types (cyclic, symmetry) etc. are allowed.
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patchInfo
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{
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type patch;
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inGroups (meshedPatches);
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}
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//- Optional increment (on top of max level) in small gaps
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//gapLevelIncrement 2;
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//- Optional angle to detect small-large cell situation
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// perpendicular to the surface. Is the angle of face w.r.t.
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// the local surface normal. Use on flat(ish) surfaces only.
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// Otherwise leave out or set to negative number.
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//perpendicularAngle 10;
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//- Optional faceZone and (for closed surface) cellZone with
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// how to select the cells that are in the cellZone
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// (inside / outside / specified insidePoint)
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// The orientation of the faceZone is
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// - if on cellZone(s) : point out of (maximum) cellZone
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// - if freestanding : oriented according to surface
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//faceZone sphere;
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//cellZone sphere;
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//cellZoneInside inside; //outside/insidePoint
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//- Optional specification of what to do with faceZone faces:
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// internal : keep them as internal faces (default)
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// baffle : create baffles from them. This gives more
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// freedom in mesh motion
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// boundary : create free-standing boundary faces (baffles
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// but without the shared points)
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//faceType baffle;
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}
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}
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// Feature angle:
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// - used if min and max refinement level of a surface differ
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// - used if feature snapping (see snapControls below) is used
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resolveFeatureAngle 30;
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//- Optional increment (on top of max level) in small gaps
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//gapLevelIncrement 2;
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// Planar angle:
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// - used to determine if surface normals
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// are roughly the same or opposite. Used
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// - in proximity refinement
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// - to decide when to merge free-standing baffles
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// (if e.g. running in surfaceSimplify mode set this to 180 to
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// merge all baffles)
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// - in snapping to avoid snapping to nearest on 'wrong' side
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// of thin gap
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//
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// If not specified same as resolveFeatureAngle
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planarAngle 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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// increasing 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. Not used if there are no faceZones.
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allowFreeStandingZoneFaces true;
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// Optional: do not remove cells likely to give snapping problems
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// handleSnapProblems false;
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// Optional: switch off topological test for cells to-be-squashed
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// and use geometric test instead
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//useTopologicalSnapDetection false;
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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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// Maximum relative distance for points to be attracted by surface.
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// True distance is this factor times local maximum edge length.
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// Note: changed(corrected) w.r.t 17x! (17x used 2* tolerance)
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tolerance 2.0;
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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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// Feature snapping
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// Number of feature edge snapping iterations.
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// Leave out altogether to disable.
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nFeatureSnapIter 10;
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// Detect (geometric only) features by sampling the surface
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// (default=false).
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implicitFeatureSnap false;
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// Use castellatedMeshControls::features (default = true)
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explicitFeatureSnap true;
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// Detect features between multiple surfaces
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// (only for explicitFeatureSnap, default = false)
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multiRegionFeatureSnap false;
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// wip: disable snapping to opposite near surfaces (revert to 22x behaviour)
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// detectNearSurfacesSnap false;
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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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// Layer thickness specification. This can be specified in one of following
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// ways:
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// - expansionRatio and finalLayerThickness (cell nearest internal mesh)
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// - expansionRatio and firstLayerThickness (cell on surface)
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// - overall thickness and firstLayerThickness
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// - overall thickness and finalLayerThickness
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// - overall thickness and expansionRatio
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//
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// Note: the mode thus selected is global, i.e. one cannot override the
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// mode on a per-patch basis (only the values can be overridden)
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// Expansion factor for layer mesh
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expansionRatio 1.0;
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// Wanted thickness of the layer furthest away from the wall.
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// If relativeSizes this is relative to undistorted size of cell
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// outside layer.
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finalLayerThickness 0.3;
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// Wanted thickness of the layer next to the wall.
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// If relativeSizes this is relative to undistorted size of cell
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// outside layer.
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//firstLayerThickness 0.3;
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// Wanted overall thickness of layers.
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// If relativeSizes this is relative to undistorted size of cell
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// outside layer.
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//thickness 0.5
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// Minimum overall thickness of total layers. If for any reason layer
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// cannot be above minThickness do not add layer.
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// If relativeSizes this is relative to undistorted size of cell
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// outside layer..
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minThickness 0.25;
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// Per final patch (so not geometry!) the layer information
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// Note: This behaviour changed after 21x. Any non-mentioned patches
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// now slide unless:
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// - nSurfaceLayers is explicitly mentioned to be 0.
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// - angle to nearest surface < slipFeatureAngle (see below)
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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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// Per patch layer data
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expansionRatio 1.3;
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finalLayerThickness 0.3;
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minThickness 0.1;
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}
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// Disable any mesh shrinking and layer addition on any point of
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// a patch by setting nSurfaceLayers to 0
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frozenPatches
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{
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nSurfaceLayers 0;
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}
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}
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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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// Note: changed(corrected) w.r.t 17x! (didn't do anything in 17x)
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nGrow 0;
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// Advanced settings
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// Static analysis of starting mesh
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// When not to extrude surface. 0 is flat surface, 90 is when two faces
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// are perpendicular
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featureAngle 130;
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// Stop layer growth on highly warped cells
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maxFaceThicknessRatio 0.5;
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// Patch displacement
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// Number of smoothing iterations of surface normals
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nSmoothSurfaceNormals 1;
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// Smooth layer thickness over surface patches
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nSmoothThickness 10;
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// Medial axis analysis
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// Angle used to pick up medial axis points
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// Note: changed(corrected) w.r.t 17x! 90 degrees corresponds to 130
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// in 17x.
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minMedialAxisAngle 90;
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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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// Number of smoothing iterations of interior mesh movement direction
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nSmoothNormals 3;
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// Optional: limit the number of steps walking away from the surface.
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// Default is unlimited.
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//nMedialAxisIter 10;
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// Optional: smooth displacement after medial axis determination.
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// default is 0.
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//nSmoothDisplacement 90;
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// (wip)Optional: do not extrude a point if none of the surrounding points is
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// not extruded. Default is false.
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//detectExtrusionIsland true;
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// Mesh shrinking
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// Optional: at non-patched sides allow mesh to slip if extrusion
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// direction makes angle larger than slipFeatureAngle. Default is
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// 0.5*featureAngle.
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slipFeatureAngle 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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// 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
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// exit if it reaches this number of iterations; possibly with an
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// illegal 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 nRelaxedIter it uses the settings in
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// meshQualityControls,
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// after nRelaxedIter it uses the values in
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// meshQualityControls::relaxed.
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nRelaxedIter 20;
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// Additional reporting: if there are just a few faces where there
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// are mesh errors (after adding the layers) print their face centres.
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// This helps in tracking down problematic mesh areas.
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//additionalReporting true;
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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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// Specify mesh quality constraints in separate dictionary so can
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// be reused (e.g. checkMesh -meshQuality)
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#include "meshQualityDict"
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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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// 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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}
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// Advanced
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//// Debug flags
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//debugFlags
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//(
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// mesh // write intermediate meshes
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// intersections // write current mesh intersections as .obj files
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// featureSeeds // write information about explicit feature edge
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// // refinement
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// attraction // write attraction as .obj files
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// layerInfo // write information about layers
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//);
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//
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//// Write flags
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//writeFlags
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//(
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// scalarLevels // write volScalarField with cellLevel for postprocessing
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// layerSets // write cellSets, faceSets of faces in layer
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// layerFields // write volScalarField for layer coverage
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//);
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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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