OpenFoamのサンプル確認(パラメータやキーワードの覚書)です。
チュートリアルフォルダ:チュートリアル場所(windows)
snappyHexMeshの作業になります。
ベース
バージョン : WINDOWS v2206
引用元
<チュートリアルフォルダ>\mesh\snappyHexMesh\flange
▼ジオメトリファイル
<チュートリアルフォルダ>\resources\geometry\flange.stl.gz
結果図

作業
//チュートリアルからサンプルをコピーしておきます。// //stlのファイルもコピーしておきます。位置は下記参照。 //コマンド:メッシュ作成 blockMesh //コマンド実行 surfaceFeatureExtract //スナッピー// ※エラー発生のためファイル修正 snappyHexMesh -overwrite //ParaView用VTK変換// foamToVTK
※snappyHexMeshDictファイルを編集
(最終行)mergeTolerance 1E-6; → mergeTolerance 1E-5;
全体構造
stlの形状ファイルを用意する必要があります。
flange
├ constant
│ └ triSurface
│ └ flange.stl.gz
├ system
│ ├ blockMeshDict
│ ├ controlDict
│ ├ decomposeParDict
│ ├ fvSchemes
│ ├ fvSolution
│ ├ meshQualityDict
│ ├ snappyHexMeshDict
│ └ surfaceFeatureExtractDict
├ Allclean
└ Allrun
system
blockMeshDict
scale 1; vertices ( ( -0.03 -0.03 -0.03) ( 0.03 -0.03 -0.03) ( 0.03 0.03 -0.03) ( -0.03 0.03 -0.03) ( -0.03 -0.03 0.01) ( 0.03 -0.03 0.01) ( 0.03 0.03 0.01) ( -0.03 0.03 0.01) ); blocks ( hex (0 1 2 3 4 5 6 7) (20 16 12) simpleGrading (1 1 1) ); edges ( ); boundary ( allBoundary { type patch; faces ( (3 7 6 2) (0 4 7 3) (2 6 5 1) (1 5 4 0) (0 3 2 1) (4 5 6 7) ); } );
controlDict
application snappyHexMesh; startFrom startTime; startTime 0; stopAt endTime; endTime 50; deltaT 1; writeControl timeStep; writeInterval 20; purgeWrite 0; writeFormat ascii; writePrecision 6; writeCompression off; timeFormat general; timePrecision 6; runTimeModifiable yes;
meshQualityDict
// Include defaults parameters from master dictionary #includeEtc "caseDicts/meshQualityDict"
snappyHexMeshDict
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Which of the steps to run
castellatedMesh true;
snap true;
addLayers false;
// 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
geometry
{
flange.stl
{
type triSurfaceMesh;
name flange;
}
//- Refine a bit extra around the small centre hole
refineHole
{
type sphere;
origin (0 0 -0.012);
radius 0.003;
}
}
// Settings for the castellatedMesh generation.
castellatedMeshControls
{
// Refinement parameters
// ~~~~~~~~~~~~~~~~~~~~~
// 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
// is not 'visible' from the keepPoint. The 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
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// 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;
}
);
// 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.
// The 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
{
// Surface-wise min and max refinement level
level (2 2);
}
}
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.
// This is an outside point locationInMesh (-0.033 -0.033 0.0033);
locationInMesh (-9.23149e-05 -0.0025 -0.0025); // Inside point
// 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
{
//- Number of patch smoothing iterations 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
// (only for explicitFeatureSnap, 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_.*"
{
nSurfaceLayers 1;
}
}
// Expansion factor for layer mesh
expansionRatio 1.0;
// Wanted thickness of final added cell layer. If multiple layers
// is the 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 to extrude surface. 0 is flat surface, 90 is when two faces
// are perpendicular
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
minMedialAxisAngle 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
{
//- Maximum non-orthogonality allowed. Set to 180 to disable.
maxNonOrtho 75;
}
// 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-5;
// ************************************************************************* //
surfaceFeatureExtractDict
flange.stl { // How to obtain raw features (extractFromFile || extractFromSurface) extractionMethod extractFromSurface; // Mark edges whose adjacent surface normals are at an angle less // than includedAngle as features // - 0 : selects no edges // - 180: selects all edges includedAngle 150; // Write options // Write features to obj format for postprocessing writeObj yes; }
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