Layers in snappy collapse in some places of my solid
2 Attachment(s)
Hi FOAMers!
I am having an issue with snappyhexmesh. I have looked in this posts:
http://www.cfd-online.com/Forums/ope...d-surface.html
http://www.cfd-online.com/Forums/ope...ng-layers.html
But, they doesn't work for me :confused:
You can see in my first picture a slice of the internal mesh in the mid plane. As you can see, layers are added without a problem. But, if I move the slice a little bit, you can see that layers have collapsed, and they dissapear :(
I have changed every number on the addlayer part of snappyhexmeshdict... I really don't know what to do
I attach my snappyhexmeshdict file:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.1.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Which of the steps to run
castellatedMesh true;
snap true;
addLayers 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
{
frisbee.stl
{
type triSurfaceMesh;
name frisbee;
}
refinementBox0
{
type searchableBox;
min (-0.135 -0.135 -0.07);
max (0.135 0.135 0.0015);
}
refinementBox1
{
type searchableBox;
min (0.135 -0.07 -0.07);
max (0.6 0.04 0.02);
}
refinementBox2
{
type searchableBox;
min (0.13 -0.1 -0.05);
max (1.5 0.07 0.05);
}
refinementBox3
{
type searchableBox;
min (-0.3 -0.2 -0.1);
max (3 0.2 0.1);
}
refinementBox4
{
type searchableBox;
min (-0.45 -0.25 -0.12);
max (4.5 0.25 0.12);
}
};
// 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 640000;
// 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 6400000;
// 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 10;
// 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 3;
// 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 "frisbee.eMesh";
level 6;
}
);
// 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
{
frisbee
{
// Surface-wise min and max refinement level
level (7 9);
}
}
// Resolve sharp angles on fridges
resolveFeatureAngle 60;
// 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
{
frisbee
{
mode distance;
levels ((0.008 10));
}
refinementBox0
{
mode inside;
levels ((1e15 9));
}
refinementBox1
{
mode inside;
levels ((1e15 9));
}
refinementBox2
{
mode inside;
levels ((1e15 7));
}
refinementBox3
{
mode inside;
levels ((1e15 4));
}
refinementBox4
{
mode inside;
levels ((1e15 2));
}
}
// Mesh selection
// ~~~~~~~~~~~~~~
// After refinement patches get added for all refinementSurfaces and
// all cells intersecting the surfaces get put into these patches. The
// section reachable from the locationInMesh is kept.
// NOTE: This point should never be on a face, always inside a cell, even
// after refinement.
locationInMesh (0 0 0);
// 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 2.0;
//- Number of mesh displacement relaxation iterations.
nSolveIter 30;
//- Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 5;
//- Highly experimental and wip: 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 points on multiple surfaces (only for explicitFeatureSnap)
multiRegionFeatureSnap false;
}
// 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
{
"frisbee.*"
{
nSurfaceLayers 5;
}
}
// Expansion factor for layer mesh
expansionRatio 1.15;
//- 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.
// is the thickness of the layer furthest away from the wall.
// See relativeSizes parameter.
finalLayerThickness 0.3;
//- Minimum thickness of cell layer. If for any reason layer
// cannot be above minThickness do not add layer.
// Relative to undistorted size of cell outside layer.
// See relativeSizes parameter.
minThickness 0.1;
//- 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 17x! (didn't do anything in 17x)
nGrow 0;
// Advanced settings
// When not to extrude surface. 0 is flat surface, 90 is when two faces
// are perpendicular
featureAngle 360;
// At non-patched sides allow mesh to slip if extrusion direction makes
// angle larger than slipFeatureAngle.
slipFeatureAngle 30;
//- Maximum number of snapping relaxation iterations. Should stop
// before upon reaching a correct mesh.
nRelaxIter 3;
// Number of smoothing iterations of surface normals
nSmoothSurfaceNormals 50;
// Number of smoothing iterations of interior mesh movement direction
nSmoothNormals 50;
// Smooth layer thickness over surface patches
nSmoothThickness 100;
// Stop layer growth on highly warped cells
maxFaceThicknessRatio 1.4;
// Reduce layer growth where ratio thickness to medial
// distance is large
maxThicknessToMedialRatio 1.2;
// Angle used to pick up medial axis points
// Note: changed(corrected) w.r.t 16x! 90 degrees corresponds to 130 in 16x.
minMedianAxisAngle 90;
// Create buffer region for new layer terminations
nBufferCellsNoExtrude 0;
// Overall max number of layer addition iterations. The mesher will exit
// if it reaches this number of iterations; possibly with an illegal
// mesh.
nLayerIter 300;
}
// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
meshQualityControls
{
#include "meshQualityDict"
// Advanced
//- Number of error distribution iterations
nSmoothScale 4;
//- amount to scale back displacement at error points
errorReduction 0.75;
// Advanced
//- Number of error distribution iterations
nSmoothScale 4;
//- amount to scale back displacement at error points
errorReduction 0.75;
}
// Advanced
// Flags for optional output
// 0 : only write final meshes
// 1 : write intermediate meshes
// 2 : write volScalarField with cellLevel for postprocessing
// 4 : write current intersections as .obj files
debug 0;
// Merge tolerance. Is fraction of overall bounding box of initial mesh.
// Note: the write tolerance needs to be higher than this.
mergeTolerance 1e-6;
// ************************************************************************* //
Thank you very much indeed in advance!
Snappy takes a lot of time to be understood, I have been working for months with it... and I have to finish my thesis |
