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snappyHexMesh : refine based on curvature

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This commit is contained in:
Mattijs Janssens
2022-08-04 17:09:38 +00:00
parent 227727d413
commit 27c3d0c23b
20 changed files with 2326 additions and 35 deletions
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tutorials/mesh/snappyHexMesh/block_with_curvature/Allclean Executable file
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#!/bin/sh
cd "${0%/*}" || exit # Run from this directory
. ${WM_PROJECT_DIR:?}/bin/tools/CleanFunctions # Tutorial clean functions
#------------------------------------------------------------------------------
cleanCase0
# Remove surface and features
rm -rf constant/triSurface
rm -rf constant/extendedFeatureEdgeMesh
#------------------------------------------------------------------------------

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tutorials/mesh/snappyHexMesh/block_with_curvature/Allrun Executable file
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#!/bin/sh
cd "${0%/*}" || exit # Run from this directory
. ${WM_PROJECT_DIR:?}/bin/tools/RunFunctions # Tutorial run functions
#------------------------------------------------------------------------------
mkdir -p constant/triSurface
cp -f \
resources/geometry/curvature-box.stl.gz \
constant/triSurface
runApplication surfaceFeatureExtract
runApplication blockMesh
runApplication snappyHexMesh -overwrite
#------------------------------------------------------------------------------

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tutorials/mesh/snappyHexMesh/block_with_curvature/README.txt Normal file
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testcase to demonstrate surface-curvature-based refinement.
- starts from a single cell
- has uniform surface refinement 0
- but has curvature detection to refine up to 10
- also uses limitRegions to not refine half the domain (in x direction)
- note that there is still refinement bleeding due to the 2:1 limitation

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tutorials/mesh/snappyHexMesh/block_with_curvature/resources/geometry/curvature-box.stl.gz Normal file
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tutorials/mesh/snappyHexMesh/block_with_curvature/system/blockMeshDict Normal file
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/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2112 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
scale 1;
vertices
(
( 0 -0.2 0)
( 0.5 -0.2 0)
( 0.5 0.3 0)
( 0 0.3 0)
( 0 -0.2 0.5)
( 0.5 -0.2 0.5)
( 0.5 0.3 0.5)
( 0 0.3 0.5)
);
blocks
(
// hex (0 1 2 3 4 5 6 7) (15 10 10) simpleGrading (1 1 1)
hex (0 1 2 3 4 5 6 7) (1 1 1) simpleGrading (1 1 1)
);
edges
();
boundary
(
allBoundary
{
type patch;
faces
(
(3 7 6 2)
(1 5 4 0) //back
(2 6 5 1) //outlet
(0 4 7 3) //inlet
(0 3 2 1) //lowerWall
(4 5 6 7) //upperWall
);
}
);
// ************************************************************************* //

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tutorials/mesh/snappyHexMesh/block_with_curvature/system/controlDict Normal file
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/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2112 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
//DebugSwitches
//{
// fvGeometryScheme 1;
// highAspectRatio 1;
// basic 1;
//}
application simpleFoam;
startFrom startTime;
startTime 0;
stopAt endTime;
endTime 15000;
deltaT 1;
writeControl timeStep;
writeInterval 5000;
purgeWrite 2;
writeFormat binary;
writePrecision 15;
writeCompression off;
timeFormat general;
timePrecision 8;
runTimeModifiable false;
// ************************************************************************* //

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tutorials/mesh/snappyHexMesh/block_with_curvature/system/fvSchemes Normal file
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/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2112 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
ddtSchemes
{
}
gradSchemes
{
}
divSchemes
{
}
laplacianSchemes
{
}
interpolationSchemes
{
}
snGradSchemes
{
}
wallDist
{
}
geometry
{
type highAspectRatio;
minAspect 10;
maxAspect 100;
}
// ************************************************************************* //

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tutorials/mesh/snappyHexMesh/block_with_curvature/system/fvSolution Normal file
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/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2112 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
solvers
{
}
// ************************************************************************* //

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tutorials/mesh/snappyHexMesh/block_with_curvature/system/meshQualityDict Normal file
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/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2112 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object meshQualityDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
//- Maximum non-orthogonality allowed. Set to 180 to disable.
maxNonOrtho 65;
//- Max skewness allowed. Set to <0 to disable.
maxBoundarySkewness 20;
maxInternalSkewness 4;
//- Max concaveness allowed. Is angle (in degrees) below which concavity
// is allowed. 0 is straight face, <0 would be convex face.
// Set to 180 to disable.
maxConcave 80;
//- Minimum pyramid volume. Is absolute volume of cell pyramid.
// Set to a sensible fraction of the smallest cell volume expected.
// Set to very negative number (e.g. -1E30) to disable.
minVol 1e-13;
//- Minimum quality of the tet formed by the face-centre
// and variable base point minimum decomposition triangles and
// the cell centre. Set to very negative number (e.g. -1E30) to
// disable.
// <0 = inside out tet,
// 0 = flat tet
// 1 = regular tet
minTetQuality 1e-15;
//- Minimum face area. Set to <0 to disable.
minArea -1;
//- Minimum face twist. Set to <-1 to disable. dot product of face normal
// (itself the average of the triangle normals)
// and face centre triangles normal
minTwist 0.02;
//- Minimum normalised cell determinant. This is the determinant of all
// the areas of internal faces. It is a measure of how much of the
// outside area of the cell is to other cells. The idea is that if all
// outside faces of the cell are 'floating' (zeroGradient) the
// 'fixedness' of the cell is determined by the area of the internal faces.
// 1 = hex, <= 0 = folded or flattened illegal cell
minDeterminant 0.001;
//- Relative position of face in relation to cell centres (0.5 for orthogonal
// mesh) (0 -> 0.5)
minFaceWeight 0.05;
//- Volume ratio of neighbouring cells (0 -> 1)
minVolRatio 0.01;
//- Per triangle normal compared to that of preceding triangle. Must be >0
// for Fluent compatibility
minTriangleTwist -1;
//- If >0 : preserve cells with all points on the surface if the
// resulting volume after snapping (by approximation) is larger than
// minVolCollapseRatio times old volume (i.e. not collapsed to flat cell).
// If <0 : delete always.
//minVolCollapseRatio 0.1;
// ************************************************************************* //

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tutorials/mesh/snappyHexMesh/block_with_curvature/system/snappyHexMeshDict Normal file
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/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2112 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Which of the steps to run
castellatedMesh true;
snap false;
addLayers false;
// Optional: single region surfaces get patch names according to
// surface only. Multi-region surfaces get patch name
// surface "_ "region. Default is true
// singleRegionName false;
// Optional: avoid patch-face merging. Allows mesh to be used for
// refinement/unrefinement
// mergePatchFaces false; // default true
// Optional: preserve all generated patches. Default is to remove
// zero-sized patches.
// keepPatches true;
// 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
{
box_limit
{
type box;
min (-1000 -1000 -1000);
max (0.125 1000 1000);
}
cylinder_all
{
//- Radius 0.1m
type triSurfaceMesh;
file curvature-box.stl;
}
};
// 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 1000000;
// 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 20000000;
// The surface refinement loop might spend lots of iterations refining just
// a few cells. This setting will cause refinement to stop if
// <= minRefinementCells cells are selected for refinement. Note: it will
// at least do one iteration unless
// a: the number of cells to refine is 0
// b: minRefinementCells = -1. This is a special value indicating
// no refinement.
minRefinementCells 0;
// Allow a certain level of imbalance during refining
// (since balancing is quite expensive)
// Expressed as fraction of perfect balance (= overall number of cells /
// nProcs). 0=balance always.
maxLoadUnbalance 0.10;
// Number of buffer layers between different levels.
// 1 means normal 2:1 refinement restriction, larger means slower
// refinement.
nCellsBetweenLevels 4;
// Explicit feature edge refinement
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Specifies a level for any cell intersected by explicitly provided
// edges.
// This is a featureEdgeMesh, read from constant/triSurface for now.
// Specify 'levels' in the same way as the 'distance' mode in the
// refinementRegions (see below). The old specification
// level 2;
// is equivalent to
// levels ((0 2));
features
(
);
// 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
{
cylinder_all
{
// Surface-wise min and max refinement level. max level is only used
// for sharp angles (see 'resolveFeatureAngle')
level (0 0);
// Additional refinement for regions of high curvature. Expressed
// (bit similar to gapLevel) as:
// - number of cells per radius of curvature. (usually 1 is
// good enough)
// - starting cell level? Not used at the moment.
// - maximum cell level. This can be smaller or larger than the
// max 'surface' level
// - minumum curvature radius to ignore (expressed as a cell level).
// This can be used to avoid detecting small sharp surface
// features. Set to -1 to ignore.
//
// Sometimes you want more refinement than sharp features since
// these can be done with feature edge snapping (so can leave
// 'level (0 0)')
curvatureLevel (10 0 10 -1);
// To trigger small feature refinement
//gapLevel (1 0 1);
}
}
// Feature angle:
// - used if min and max refinement level of a surface differ
// - used if feature snapping (see snapControls below) is used
resolveFeatureAngle 45;
// 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
// increasing 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
{
}
// Optionally limit refinement in geometric region. This limits all
// refinement (from features, refinementSurfaces, refinementRegions)
// in a given geometric region. The syntax is exactly the same as for the
// refinementRegions; the cell level now specifies the upper limit
// for any cell. (a special setting is cell level -1 which will remove
// any cells inside the region). Note that it does not override the
// refinement constraints given by the nCellsBetweenLevels setting.
limitRegions
{
box_limit
{
mode inside;
// Don't refine at all inside 'box_limit'
levels ((10000 0));
}
}
// 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 location(s)InMesh is kept.
// NOTE: This point should never be on a face, always inside a cell, even
// after refinement.
//
// There are two different ways of specifying the regions to keep:
// 1. a single locationInMesh. This is the unzoned part of the mesh.
// All the 'zoned' surfaces are marked as such
// in the refinementSurfaces with the faceZone and cellZone keywords.
// It is illegal to have the locationInMesh inside a surface for which
// a cellZone is specified.
//
// or
//
// 2. multiple locationsInMesh, with per location the name of the cellZone.
// This uses walking to determine zones and automatically creates
// faceZones on the outside of cellZones. The special name 'none' is
// used to indicate the unzoned/background part of the mesh.
// Ad 1. Specify a single location and how to treat faces inbetween
// cellZones
locationInMesh (0.101 0.101 0.101);
// Whether any faceZones (as specified in the refinementSurfaces)
// are only on the boundary of corresponding cellZones.
// Not used if there are no faceZones. The behaviour has changed
// with respect to previous versions:
// true : all intersections with surface are put in faceZone
// (same behaviour as before)
// false : depending on the type of surface intersected:
// - if intersecting surface has faceZone only (so no cellZone)
// leave in faceZone (so behave as if set to true) (= changed
// behaviour)
// - if intersecting surface has faceZone and cellZone
// remove if inbetween same cellZone or if on boundary
// (same behaviour as before)
allowFreeStandingZoneFaces true;
// 2. Specify multiple locations with optional cellZones for the
// regions (use cellZone "none" to specify the unzoned cells)
// FaceZones are automatically constructed from the
// names of the cellZones: <cellZoneA> _to_ <cellZoneB>
// where the cellZoneA is the lowest numbered cellZone (non-cellZone
// cells are in a special region called "none" which is always
// last).
// Optional locations that should not be reachable from
// location(s)InMesh
// locationsOutsideMesh ((100 100 100));
// Optional: do not remove cells likely to give snapping problems
// handleSnapProblems false;
// Optional: switch off topological test for cells to-be-squashed
// and use geometric test instead
//useTopologicalSnapDetection false;
// Optional: do not refine surface cells with opposite faces of
// differing refinement levels
//interfaceRefine false;
// Optional: use an erosion instead of region assignment to allocate
// left-over cells to the background region (i.e. make cellZones
// consistent with the intersections of the surface).
// Erosion is specified as a number of erosion iterations.
// Erosion has less chance of bleeding and changing the zone
// for a complete region.
//nCellZoneErodeIter 2;
}
// Settings for the snapping.
snapControls
{
// Number of patch smoothing iterations before finding correspondence
// to surface
nSmoothPatch 3;
// Optional: number of smoothing iterations for internal points on
// refinement interfaces. This will reduce non-orthogonality on
// refinement interfaces.
//nSmoothInternal $nSmoothPatch;
// Maximum relative distance for points to be attracted by surface.
// True distance is this factor times local maximum edge length.
tolerance 1.0;
// Number of mesh displacement relaxation iterations.
nSolveIter 30;
// Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 5;
// (wip) disable snapping to opposite near surfaces (revert to 22x
// behaviour)
// detectNearSurfacesSnap false;
// Feature snapping
// Number of feature edge snapping iterations.
// Leave out altogether to disable.
nFeatureSnapIter 10;
// Detect (geometric only) features by sampling the surface
// (default=false).
implicitFeatureSnap false;
// Use castellatedMeshControls::features (default = true)
explicitFeatureSnap true;
// Detect features between multiple surfaces
// (only for explicitFeatureSnap, default = false)
multiRegionFeatureSnap false;
//- When to run face splitting (never at first iteration, always
// at last iteration). Is interval. Default -1 (disabled)
//nFaceSplitInterval 5;
// (wip) Optional for explicit feature snapping:
//- Detect baffle edges. Default is true.
//detectBaffles false;
//- On any faces where points are on multiple regions (see
// multiRegionFeatureSnap) have the other points follow these points
// instead of having their own independent movement, i.e. have snapping
// to multi-region edges/points take priority. This might aid snapping
// to sharp edges that are also region edges. The default is false.
//releasePoints true;
//- Walk along feature edges, adding missing ones. Default is true.
//stringFeatures false;
//- If diagonal attraction also attract other face points. Default is
// false
//avoidDiagonal true;
//- When splitting what concave faces to leave intact. Default is 45
// degrees.
//concaveAngle 30;
//- When splitting the minimum area ratio of faces. If face split
// causes ratio of area less than this do not split. Default is 0.3
//minAreaRatio 0.3;
//- Attract points only to the surface they originate from. Default
// false. This can improve snapping of intersecting surfaces.
strictRegionSnap 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;
// Layer thickness specification. This can be specified in one of following
// ways:
// - expansionRatio and finalLayerThickness (cell nearest internal mesh)
// - expansionRatio and firstLayerThickness (cell on surface)
// - overall thickness and firstLayerThickness
// - overall thickness and finalLayerThickness
// - overall thickness and expansionRatio
//
// Note: the mode thus selected is global, i.e. one cannot override the
// mode on a per-patch basis (only the values can be overridden)
// Expansion factor for layer mesh
expansionRatio 1.5;
// Wanted thickness of the layer furthest away from the wall.
// If relativeSizes this is relative to undistorted size of cell
// outside layer.
finalLayerThickness 0.3;
// Wanted thickness of the layer next to the wall.
// If relativeSizes this is relative to undistorted size of cell
// outside layer.
//firstLayerThickness 0.3;
// Wanted overall thickness of layers.
// If relativeSizes this is relative to undistorted size of cell
// outside layer.
//thickness 0.5
// Minimum overall thickness of total layers. If for any reason layer
// cannot be above minThickness do not add layer.
// If relativeSizes this is relative to undistorted size of cell
// outside layer..
minThickness 0.1;
// Per final patch or faceZone (so not geometry!) the layer information
// Note: This behaviour changed after 21x. Any non-mentioned patches
// now slide unless:
// - nSurfaceLayers is explicitly mentioned to be 0.
// - angle to nearest surface < slipFeatureAngle (see below)
layers
{
"internalFace.*" {nSurfaceLayers 20; }
aerofoil
{
nSurfaceLayers 20;
}
}
// 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.
// Note: changed(corrected) w.r.t 1.7.x! (didn't do anything in 1.7.x)
nGrow -1;
// Advanced settings
// Static analysis of starting mesh
// When not to extrude surface. 0 is flat surface, 90 is when two faces
// are perpendicular. Note: was not working correctly < 1806
featureAngle 180;
// When to merge patch faces. Default is featureAngle. Useful when
// featureAngle is large.
//mergePatchFacesAngle 45;
// Stop layer growth on highly warped cells
maxFaceThicknessRatio 1000;//0.5;
// Patch displacement
// Number of smoothing iterations of surface normals
nSmoothSurfaceNormals 1;
// Smooth layer thickness over surface patches
nSmoothThickness 10;
// Choice of mesh shrinking algorithm
// Optional mesh shrinking algorithm (default is displacementMedialAxis)
// The displacementMotionSolver is a wrapper around the displacement
// motion solvers. It needs specification of the solver to use and
// its control dictionary.
//meshShrinker displacementMotionSolver;
//solver displacementLaplacian;
//displacementLaplacianCoeffs
//{
// diffusivity quadratic inverseDistance
// (
// sphere.stl_firstSolid
// maxY
// );
//}
// Note that e.g. displacementLaplacian needs entries in
// fvSchemes, fvSolution. Also specify a minIter > 1 when solving
// cellDisplacement since otherwise solution might not be sufficiently
// accurate on points.
// Medial axis analysis (for use with default displacementMedialAxis)
// Angle used to pick up medial axis points
// Note: changed(corrected) w.r.t 1.7.x! 90 degrees corresponds to 130
// in 1.7.x.
minMedialAxisAngle 90;
// Reduce layer growth where ratio thickness to medial
// distance is large
maxThicknessToMedialRatio 0.3;
// Number of smoothing iterations of interior mesh movement direction
nSmoothNormals 3;
// Optional: limit the number of steps walking away from the surface.
// Default is unlimited.
//nMedialAxisIter 10;
// Optional: smooth displacement after medial axis determination.
// default is 0.
//nSmoothDisplacement 90;
// (wip)Optional: do not extrude any point where
// (false) : all surrounding faces are not fully extruded
// (true) : all surrounding points are not extruded
// Default is false.
//detectExtrusionIsland true;
// Optional: do not extrude around sharp edges if both faces are not
// fully extruded i.e. if one of the faces on either side would
// become a wedge.
// Default is 0.5*featureAngle. Set to -180 always attempt extrusion
//layerTerminationAngle 25;
// Optional: disable shrinking of edges that have one (or two) points
// on an extruded patch.
// Default is false to enable single/two cell thick channels to still
// have layers. In <=1806 this was true by default. On larger gaps it
// should have no effect.
//disableWallEdges true;
// Optional: at non-patched sides allow mesh to slip if extrusion
// direction makes angle larger than slipFeatureAngle. Default is
// 0.5*featureAngle.
slipFeatureAngle 10;
// Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 5;
// Mesh shrinking
// Create buffer region for new layer terminations, i.e. gradually
// step down number of layers. Set to <0 to terminate layer in one go.
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 nRelaxedIter it uses the settings in
// meshQualityControls,
// after nRelaxedIter it uses the values in
// meshQualityControls::relaxed.
nRelaxedIter 0;
// Additional reporting: if there are just a few faces where there
// are mesh errors (after adding the layers) print their face centres.
// This helps in tracking down problematic mesh areas.
//additionalReporting true;
}
// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
meshQualityControls
{
// Specify mesh quality constraints in separate dictionary so can
// be reused (e.g. checkMesh -meshQuality)
#include "meshQualityDict"
minDeterminant 1e-8;
// 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;
minTetQuality -1e30;
minTwist -1;
}
// Advanced
// Number of error distribution iterations
nSmoothScale 4;
// amount to scale back displacement at error points
errorReduction 0.75;
}
// Debug flags
//debugFlags
//(
// mesh // write intermediate meshes
//);
//// Format for writing lines. E.g. leak path. Default is vtk format.
//setFormat ensight;
// Merge tolerance. Is fraction of overall bounding box of initial mesh.
// Note: the write tolerance needs to be higher than this.
mergeTolerance 1e-6;
// ************************************************************************* //

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/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2112 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Which of the steps to run
castellatedMesh true;
snap false;
addLayers false;
// Optional: single region surfaces get patch names according to
// surface only. Multi-region surfaces get patch name
// surface "_ "region. Default is true
// singleRegionName false;
// Optional: avoid patch-face merging. Allows mesh to be used for
// refinement/unrefinement
// mergePatchFaces false; // default true
// Optional: preserve all generated patches. Default is to remove
// zero-sized patches.
// keepPatches true;
// 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
{
all
{
type box;
min (-1000 -1000 -1000);
max (1000 1000 1000);
}
cylinder_all
{
//- Radius 0.1m
type triSurfaceMesh;
file curvature-box.stl;
}
};
// 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 1000000;
// 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 20000000;
// The surface refinement loop might spend lots of iterations refining just
// a few cells. This setting will cause refinement to stop if
// <= minRefinementCells cells are selected for refinement. Note: it will
// at least do one iteration unless
// a: the number of cells to refine is 0
// b: minRefinementCells = -1. This is a special value indicating
// no refinement.
minRefinementCells 0;
// Allow a certain level of imbalance during refining
// (since balancing is quite expensive)
// Expressed as fraction of perfect balance (= overall number of cells /
// nProcs). 0=balance always.
maxLoadUnbalance 0.10;
// Number of buffer layers between different levels.
// 1 means normal 2:1 refinement restriction, larger means slower
// refinement.
nCellsBetweenLevels 4;
// Explicit feature edge refinement
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Specifies a level for any cell intersected by explicitly provided
// edges.
// This is a featureEdgeMesh, read from constant/triSurface for now.
// Specify 'levels' in the same way as the 'distance' mode in the
// refinementRegions (see below). The old specification
// level 2;
// is equivalent to
// levels ((0 2));
features
(
);
// 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
{
cylinder_all
{
// Surface-wise min and max refinement level. max level is only used
// for sharp angles (see 'resolveFeatureAngle')
level (0 0);
// Additional refinement for regions of high curvature. Expressed
// (bit similar to gapLevel) as:
// - number of cells per radius of curvature. (usually 1 is
// good enough)
// - starting cell level? Not used at the moment.
// - maximum cell level. This can be smaller or larger than the
// max 'surface' level
// - minumum curvature radius to ignore (expressed as a cell level).
// This can be used to avoid detecting small sharp surface
// features. Set to -1 to ignore.
//
// Sometimes you want more refinement than sharp features since
// these can be done with feature edge snapping (so can leave
// 'level (0 0)')
curvatureLevel (10 0 10 -1);
// To trigger small feature refinement
//gapLevel (1 0 1);
}
}
//- looking at triangle mesh itself? E.g. cables with 3 triangles do not need
//refinement.
//- what about 90 degree angles. Do NOT refine.
//Refine always. With chamfer: currently not
// detected. So curvature refinement is just extension of resolveFeatureAngle
// mechanism.
//- disconnected surfaces. Currently not needed. Can also only be on single patch.
//- triangle clouds. Currently not needed.
//- limited to volume as well (like gapLevel). Not currently. Happy with either
// - global (like resolveFeatureAngle)
// - per patch (like resolveFeatureAngle)
// Feature angle:
// - used if min and max refinement level of a surface differ
// - used if feature snapping (see snapControls below) is used
resolveFeatureAngle 45;
// 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
// increasing 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
{
all
{
mode inside;
// Dummy base level
levels ((10000 0));
// If cells
// - have level 0..9
// - and are in a gap < 3 cell sizes across
// - with the gap on the inside ('inside'), outside ('outside')
// or both ('mixed') of the surface
// refine them
//gapLevel (4 0 10);
//gapMode outside;
}
}
// Optionally limit refinement in geometric region. This limits all
// refinement (from features, refinementSurfaces, refinementRegions)
// in a given geometric region. The syntax is exactly the same as for the
// refinementRegions; the cell level now specifies the upper limit
// for any cell. (a special setting is cell level -1 which will remove
// any cells inside the region). Note that it does not override the
// refinement constraints given by the nCellsBetweenLevels setting.
limitRegions
{
}
// 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 location(s)InMesh is kept.
// NOTE: This point should never be on a face, always inside a cell, even
// after refinement.
//
// There are two different ways of specifying the regions to keep:
// 1. a single locationInMesh. This is the unzoned part of the mesh.
// All the 'zoned' surfaces are marked as such
// in the refinementSurfaces with the faceZone and cellZone keywords.
// It is illegal to have the locationInMesh inside a surface for which
// a cellZone is specified.
//
// or
//
// 2. multiple locationsInMesh, with per location the name of the cellZone.
// This uses walking to determine zones and automatically creates
// faceZones on the outside of cellZones. The special name 'none' is
// used to indicate the unzoned/background part of the mesh.
// Ad 1. Specify a single location and how to treat faces inbetween
// cellZones
locationInMesh (0.101 0.101 0.101);
// Whether any faceZones (as specified in the refinementSurfaces)
// are only on the boundary of corresponding cellZones.
// Not used if there are no faceZones. The behaviour has changed
// with respect to previous versions:
// true : all intersections with surface are put in faceZone
// (same behaviour as before)
// false : depending on the type of surface intersected:
// - if intersecting surface has faceZone only (so no cellZone)
// leave in faceZone (so behave as if set to true) (= changed
// behaviour)
// - if intersecting surface has faceZone and cellZone
// remove if inbetween same cellZone or if on boundary
// (same behaviour as before)
allowFreeStandingZoneFaces true;
// 2. Specify multiple locations with optional cellZones for the
// regions (use cellZone "none" to specify the unzoned cells)
// FaceZones are automatically constructed from the
// names of the cellZones: <cellZoneA> _to_ <cellZoneB>
// where the cellZoneA is the lowest numbered cellZone (non-cellZone
// cells are in a special region called "none" which is always
// last).
// Optional locations that should not be reachable from
// location(s)InMesh
// locationsOutsideMesh ((100 100 100));
// Optional: do not remove cells likely to give snapping problems
// handleSnapProblems false;
// Optional: switch off topological test for cells to-be-squashed
// and use geometric test instead
//useTopologicalSnapDetection false;
// Optional: do not refine surface cells with opposite faces of
// differing refinement levels
//interfaceRefine false;
// Optional: use an erosion instead of region assignment to allocate
// left-over cells to the background region (i.e. make cellZones
// consistent with the intersections of the surface).
// Erosion is specified as a number of erosion iterations.
// Erosion has less chance of bleeding and changing the zone
// for a complete region.
//nCellZoneErodeIter 2;
}
// Settings for the snapping.
snapControls
{
// Number of patch smoothing iterations before finding correspondence
// to surface
nSmoothPatch 3;
// Optional: number of smoothing iterations for internal points on
// refinement interfaces. This will reduce non-orthogonality on
// refinement interfaces.
//nSmoothInternal $nSmoothPatch;
// Maximum relative distance for points to be attracted by surface.
// True distance is this factor times local maximum edge length.
tolerance 1.0;
// Number of mesh displacement relaxation iterations.
nSolveIter 30;
// Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 5;
// (wip) disable snapping to opposite near surfaces (revert to 22x
// behaviour)
// detectNearSurfacesSnap false;
// Feature snapping
// Number of feature edge snapping iterations.
// Leave out altogether to disable.
nFeatureSnapIter 10;
// Detect (geometric only) features by sampling the surface
// (default=false).
implicitFeatureSnap false;
// Use castellatedMeshControls::features (default = true)
explicitFeatureSnap true;
// Detect features between multiple surfaces
// (only for explicitFeatureSnap, default = false)
multiRegionFeatureSnap false;
//- When to run face splitting (never at first iteration, always
// at last iteration). Is interval. Default -1 (disabled)
//nFaceSplitInterval 5;
// (wip) Optional for explicit feature snapping:
//- Detect baffle edges. Default is true.
//detectBaffles false;
//- On any faces where points are on multiple regions (see
// multiRegionFeatureSnap) have the other points follow these points
// instead of having their own independent movement, i.e. have snapping
// to multi-region edges/points take priority. This might aid snapping
// to sharp edges that are also region edges. The default is false.
//releasePoints true;
//- Walk along feature edges, adding missing ones. Default is true.
//stringFeatures false;
//- If diagonal attraction also attract other face points. Default is
// false
//avoidDiagonal true;
//- When splitting what concave faces to leave intact. Default is 45
// degrees.
//concaveAngle 30;
//- When splitting the minimum area ratio of faces. If face split
// causes ratio of area less than this do not split. Default is 0.3
//minAreaRatio 0.3;
//- Attract points only to the surface they originate from. Default
// false. This can improve snapping of intersecting surfaces.
strictRegionSnap 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;
// Layer thickness specification. This can be specified in one of following
// ways:
// - expansionRatio and finalLayerThickness (cell nearest internal mesh)
// - expansionRatio and firstLayerThickness (cell on surface)
// - overall thickness and firstLayerThickness
// - overall thickness and finalLayerThickness
// - overall thickness and expansionRatio
//
// Note: the mode thus selected is global, i.e. one cannot override the
// mode on a per-patch basis (only the values can be overridden)
// Expansion factor for layer mesh
expansionRatio 1.5;
// Wanted thickness of the layer furthest away from the wall.
// If relativeSizes this is relative to undistorted size of cell
// outside layer.
finalLayerThickness 0.3;
// Wanted thickness of the layer next to the wall.
// If relativeSizes this is relative to undistorted size of cell
// outside layer.
//firstLayerThickness 0.3;
// Wanted overall thickness of layers.
// If relativeSizes this is relative to undistorted size of cell
// outside layer.
//thickness 0.5
// Minimum overall thickness of total layers. If for any reason layer
// cannot be above minThickness do not add layer.
// If relativeSizes this is relative to undistorted size of cell
// outside layer..
minThickness 0.1;
// Per final patch or faceZone (so not geometry!) the layer information
// Note: This behaviour changed after 21x. Any non-mentioned patches
// now slide unless:
// - nSurfaceLayers is explicitly mentioned to be 0.
// - angle to nearest surface < slipFeatureAngle (see below)
layers
{
"internalFace.*" {nSurfaceLayers 20; }
aerofoil
{
nSurfaceLayers 20;
}
}
// 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.
// Note: changed(corrected) w.r.t 1.7.x! (didn't do anything in 1.7.x)
nGrow -1;
// Advanced settings
// Static analysis of starting mesh
// When not to extrude surface. 0 is flat surface, 90 is when two faces
// are perpendicular. Note: was not working correctly < 1806
featureAngle 180;
// When to merge patch faces. Default is featureAngle. Useful when
// featureAngle is large.
//mergePatchFacesAngle 45;
// Stop layer growth on highly warped cells
maxFaceThicknessRatio 1000;//0.5;
// Patch displacement
// Number of smoothing iterations of surface normals
nSmoothSurfaceNormals 1;
// Smooth layer thickness over surface patches
nSmoothThickness 10;
// Choice of mesh shrinking algorithm
// Optional mesh shrinking algorithm (default is displacementMedialAxis)
// The displacementMotionSolver is a wrapper around the displacement
// motion solvers. It needs specification of the solver to use and
// its control dictionary.
//meshShrinker displacementMotionSolver;
//solver displacementLaplacian;
//displacementLaplacianCoeffs
//{
// diffusivity quadratic inverseDistance
// (
// sphere.stl_firstSolid
// maxY
// );
//}
// Note that e.g. displacementLaplacian needs entries in
// fvSchemes, fvSolution. Also specify a minIter > 1 when solving
// cellDisplacement since otherwise solution might not be sufficiently
// accurate on points.
// Medial axis analysis (for use with default displacementMedialAxis)
// Angle used to pick up medial axis points
// Note: changed(corrected) w.r.t 1.7.x! 90 degrees corresponds to 130
// in 1.7.x.
minMedialAxisAngle 90;
// Reduce layer growth where ratio thickness to medial
// distance is large
maxThicknessToMedialRatio 0.3;
// Number of smoothing iterations of interior mesh movement direction
nSmoothNormals 3;
// Optional: limit the number of steps walking away from the surface.
// Default is unlimited.
//nMedialAxisIter 10;
// Optional: smooth displacement after medial axis determination.
// default is 0.
//nSmoothDisplacement 90;
// (wip)Optional: do not extrude any point where
// (false) : all surrounding faces are not fully extruded
// (true) : all surrounding points are not extruded
// Default is false.
//detectExtrusionIsland true;
// Optional: do not extrude around sharp edges if both faces are not
// fully extruded i.e. if one of the faces on either side would
// become a wedge.
// Default is 0.5*featureAngle. Set to -180 always attempt extrusion
//layerTerminationAngle 25;
// Optional: disable shrinking of edges that have one (or two) points
// on an extruded patch.
// Default is false to enable single/two cell thick channels to still
// have layers. In <=1806 this was true by default. On larger gaps it
// should have no effect.
//disableWallEdges true;
// Optional: at non-patched sides allow mesh to slip if extrusion
// direction makes angle larger than slipFeatureAngle. Default is
// 0.5*featureAngle.
slipFeatureAngle 10;
// Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 5;
// Mesh shrinking
// Create buffer region for new layer terminations, i.e. gradually
// step down number of layers. Set to <0 to terminate layer in one go.
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 nRelaxedIter it uses the settings in
// meshQualityControls,
// after nRelaxedIter it uses the values in
// meshQualityControls::relaxed.
nRelaxedIter 0;
// Additional reporting: if there are just a few faces where there
// are mesh errors (after adding the layers) print their face centres.
// This helps in tracking down problematic mesh areas.
//additionalReporting true;
}
// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
meshQualityControls
{
// Specify mesh quality constraints in separate dictionary so can
// be reused (e.g. checkMesh -meshQuality)
#include "meshQualityDict"
minDeterminant 1e-8;
// 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;
minTetQuality -1e30;
minTwist -1;
}
// Advanced
// Number of error distribution iterations
nSmoothScale 4;
// amount to scale back displacement at error points
errorReduction 0.75;
}
// Advanced
// Debug flags
debugFlags
(
// mesh // write intermediate meshes
// intersections // write current mesh intersections as .obj files
// featureSeeds // write information about explicit feature edge
// // refinement
// attraction // write attraction as .obj files
// layerInfo // write information about layers
);
//
//// Write flags
//writeFlags
//(
// scalarLevels // write volScalarField with cellLevel for postprocessing
// layerSets // write cellSets, faceSets of faces in layer
// layerFields // write volScalarField for layer coverage
//);
//// Format for writing lines. E.g. leak path. Default is vtk format.
//setFormat ensight;
// Merge tolerance. Is fraction of overall bounding box of initial mesh.
// Note: the write tolerance needs to be higher than this.
mergeTolerance 1e-6;
// ************************************************************************* //

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/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2112 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object surfaceFeatureExtractDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
//- temp dictionary with common settings
_surfaceExtract
{
// Extract raw features (none | 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 120;
// Output surface curvature
curvature true;
// Do not mark region edges
geometricTestOnly yes;
// Generate additional intersection features (none | self | region)
intersectionMethod none;
// Tolerance for surface intersections
// tolerance 1e-3;
// Output options:
// Write features to obj format for postprocessing
writeObj yes;
// Write closeness/curvature/proximity fields as VTK for postprocessing
writeVTK yes;
}
curvature-box.stl
{
$_surfaceExtract;
}
//- Remove temp from dictionary so it doesn't think it is a surface
#remove _surfaceExtract
// ************************************************************************* //