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-   -   snappyHexMesh beginner problems (https://www.cfd-online.com/Forums/openfoam-meshing-snappyhexmesh/70157-snappyhexmesh-beginner-problems.html)

 sErik November 16, 2009 09:14

snappyHexMesh beginner problems

Hello everyone,

I'm a beginner with OF and trying to sHM a little test file, but i have several problems.

# 1
How can I specify apropriate boundary-, faces-, neighbour-, points- and owner-files for my specail case?
They won't be created by sHM, right? But how can I then get the right entries, e.g. number of vartices (for my case) into those files?

#2
When executing snappyHexMesh, I reviece following error message:

__________________________________________________ ________________

Create time

Create mesh for time = 0

Read mesh in = 0.41 s

Overall mesh bounding box : (-0.05 -0.025 -0.02) (0.05 0.025 0.02)
Relative tolerance : 1e-06
Absolute matching distance : 1.18743e-07

Read refinement surfaces in = 0 s

Refinement level 4 for all cells inside box.stl
shellSurfaces : Flipped orientation of surface box.stl so point (150 75 60) is outside.
Read refinement shells in = 0.01 s

Setting refinement level of surface to be consistent with shells.
Checked shell refinement in = 0 s

Determining initial surface intersections
-----------------------------------------

Edge intersection testing:
Number of edges : 58750
Number of edges to retest : 58750
Number of intersected edges : 0
Calculated surface intersections in = 0.43 s

Initial mesh : cells:18750 faces:58750 points:21346
Cells per refinement level:
0 18750

----------------------------------

Patch Region
----- ------
refinementBox:

8 refinementBox_region0

Added patches in = 0 s

Selecting decompositionMethod hierarchical

Refinement phase
----------------

Point (3 3 0.43) is not inside the mesh or on a face or edge.
Bounding box of the mesh:(-0.05 -0.025 -0.02) (0.05 0.025 0.02)

From function refinementParameters::findCells(const polyMesh&) const
in file autoHexMesh/autoHexMeshDriver/refinementParameters/refinementParameters.C at line 104.

FOAM exiting

__________________________________________________ ________________

Does this mean, my original blockMesh is too smal? Do I have to enlarge it?

Here's my snappyHesMeshDict file:
__________________________________________________ ________________

geometry
{
box.stl
{
type triSurfaceMesh;
name box;
};

refinementBox
{
type searchableBox;
min (-1.0 -0.7 0.0);
max ( 8.0 0.7 2.5);
}

};

castellatedMeshControls
{
maxLocalCells 1000000;

maxGlobalCells 2000000;

minRefinementCells 100;

nCellsBetweenLevels 1;

// features
// (
// {
// file "fridgeA.eMesh";
// level 3;
// }
//
// );

refinementSurfaces
{
box.stl
{
level (1 3);
}
}

resolveFeatureAngle 60;

refinementRegions
{
box
{
mode inside;
levels ((1.0 4));
}
}
locationInMesh (3 3 0.43);
}

snapControls
{
nSmoothPatch 3;

tolerance 4.0;

nSolveIter 30;

nRelaxIter 5;
}

{
relativeSizes false;

layers
{
box.stl
{
nSurfaceLayers 3;
}

}

expansionRatio 1.0;

finalLayerThickness 0.5;

minThickness 0.25;

nGrow 0;

featureAngle 60;

nRelaxIter 5;

nSmoothSurfaceNormals 1;

nSmoothNormals 3;

nSmoothThickness 10;

maxFaceThicknessRatio 0.5;

maxThicknessToMedialRatio 0.3;

minMedianAxisAngle 130;

nBufferCellsNoExtrude 0;

nLayerIter 50;
}

meshQualityControls
{
maxNonOrtho 65;

maxBoundarySkewness 20;
maxInternalSkewness 4;

maxConcave 80;

minFlatness 0.5;

minVol 1e-13;

minArea -1;

minTwist 0.05;

minDeterminant 0.001;

minFaceWeight 0.05;

minVolRatio 0.01;

minTriangleTwist -1;

nSmoothScale 4;

errorReduction 0.75;
}

debug 0;

mergeTolerance 1E-6;
__________________________________________________ _______________

 sErik November 16, 2009 09:47

All right, I enlarged the blockMes and now sHM basicly running. :-)

Although I think, there need to be more improvement on the sHMDict, because it's working quite long on such an easy surface, I entered.

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