Kryo 
September 10, 2012 06:13 
Add Mesh Layers doesnt work on the whole surface
Hello,
I just tried to make a simple mesh with snappyHexMesh, and everything worked quite well so far.
But now I am at a point, where I cannot find a solution to my current problem.
I got a simple "rocket" which exists of a cylinder and a cone as tip and rear.
When creating the mesh it adds the layers on the surface correctly, but only on the cylindrical part.
you can find a screenshot here: https://dl.dropbox.com/u/3545765/layersproblem.png
as you see the layers stop at the edge, same on the tip and rear side.
my snappyhexmeshdict as follows:
Code:
addLayersControls
{
relativeSizes true;
layers
{
rocketbody_rocketbodysurf
{
nSurfaceLayers 20;
}
}
expansionRatio 1.1;
finalLayerThickness 1e1;
minThickness 1e10;
nGrow 1;
featureAngle 310;
nRelaxIter 3;
nSmoothSurfaceNormals 1;
nSmoothNormals 3;
nSmoothThickness 10;
maxFaceThicknessRatio 0.5;
maxThicknessToMedialRatio 0.3;
minMedianAxisAngle 180;
nBufferCellsNoExtrude 0;
nLayerIter 1500;
}
changing feature angle does impact it slightly, but still even with 360° it doesnt work. The STL file is all in one, so there is only one surface which is rocketbody_rocketbodysurf.
Anyone any ideas? Thanks in advance!
EDIT: maybe the output would also be interesting:
Code:
Shrinking and layer addition phase

Using mesh parameters
{
maxNonOrtho 180;
maxBoundarySkewness 20;
maxInternalSkewness 4;
maxConcave 180;
minVol 1e13;
minTetQuality 1e30;
minArea 1;
minTwist 0.02;
minDeterminant 0.001;
minFaceWeight 0.02;
minVolRatio 0.01;
minTriangleTwist 1;
nSmoothScale 4;
errorReduction 0.75;
}
Merging all faces of a cell

 which are on the same patch
 which make an angle < 310 degrees
(cos:0.642788)
 as long as the resulting face doesn't become concave by more than 90 degrees
(0=straight, 180=fully concave)
Merging 0 sets of faces.
No faces merged ...
Merging all points on surface that
 are used by only two boundary faces and
 make an angle with a cosine of more than 0.642788.
No straight edges simplified and no points removed ...
Checking mesh manifoldness ...
Checking initial mesh ...
Checking faces in error :
faces with face pyramid volume < 1e13 : 0
faces with facedecomposition tet quality < 1e30 : 0
faces with skewness > 4 (internal) or 20 (boundary) : 0
faces with interpolation weights (0..1) < 0.02 : 0
faces with volume ratio of neighbour cells < 0.01 : 0
faces with face twist < 0.02 : 0
faces on cells with determinant < 0.001 : 0
Detected 0 illegal faces (concave, zero area or negative cell pyramid volume)
Adding in total 0 interprocessor patches to handle extrusion of nonmanifold processor boundaries.
Constructing mesh displacer ...
Handling points with inconsistent layer specification ...
Handling nonmanifold points ...
Checking patch manifoldness ...
Outside of local patch is multiply connected across edges or points at 0 points.
Set displacement to zero for all 0 nonmanifold points
Handling feature edges ...
Handling cells with warped patch faces ...
Set displacement to zero on 0 warped faces since layer would be > 0.5 of the size of the bounding box.
Growing nonextrusion points by one layer ...
Set displacement to zero for an additional 0 points.
patch faces layers avg thickness[m]
nearwall overall
    
rocketbody_rocketbodysurf 4536 20 0.00511 0.293
medialAxisSmoothingInfo : Calculate distance to Medial Axis ...
shrinkMeshDistance : Smoothing normals ...
Iteration 0 residual 0.0105
shrinkMeshDistance : Smoothing normals ...
shrinkMeshDistance : Smoothing normals in interior ...
Iteration 0 residual 0.0632
Layer addition iteration 0

Prevented extrusion on 0 coupled patch points during syncPatchDisplacement.
Determining displacement for added points according to pointNormal ...
Prevented extrusion on 0 coupled patch points during syncPatchDisplacement.
shrinkMeshMedialDistance : Smoothing using Medial Axis ...
shrinkMeshMedialDistance : Reduce layer thickness at 0 nodes where thickness to medial axis distance is large
shrinkMeshDistance : Removing isolated regions ...
Number isolated points extrusion stopped : 0
shrinkMeshDistance : Smoothing field ...
Iteration 0 residual 9.04e05
shrinkMeshMedialDistance : Moving mesh ...
Iteration 0
Moving mesh using diplacement scaling : min:1 max:1
Checking faces in error :
faces with face pyramid volume < 1e13 : 0
faces with facedecomposition tet quality < 1e30 : 0
faces with skewness > 4 (internal) or 20 (boundary) : 0
faces with interpolation weights (0..1) < 0.02 : 0
faces with volume ratio of neighbour cells < 0.01 : 0
faces with face twist < 0.02 : 0
faces on cells with determinant < 0.001 : 0
shrinkMeshMedialDistance : Successfully moved mesh
shrinkMeshMedialDistance : Finished moving mesh ...
Prevented extrusion on 0 coupled patch points during syncPatchDisplacement.
truncateDisplacement : Unextruded 0 faces due to nonconsecutive vertices being extruded.
truncateDisplacement : Unextruded 0 faces due to stringed edges with inconsistent extrusion.
Setting up information for layer truncation ...
Checking mesh with layer ...
Checking faces in error :
faces with face pyramid volume < 1e13 : 0
faces with facedecomposition tet quality < 1e30 : 3588
faces with skewness > 4 (internal) or 20 (boundary) : 0
faces with interpolation weights (0..1) < 0.02 : 0
faces with volume ratio of neighbour cells < 0.01 : 0
faces with face twist < 0.02 : 0
faces on cells with determinant < 0.001 : 0
Detected 3588 illegal faces (concave, zero area or negative cell pyramid volume)
Extruding 4016 out of 4536 faces (88.5%). Removed extrusion at 302 faces.
Growing nonextrusion points by one layer ...
Set displacement to zero for an additional 198 points.
Layer addition iteration 1

Prevented extrusion on 0 coupled patch points during syncPatchDisplacement.
Determining displacement for added points according to pointNormal ...
Prevented extrusion on 0 coupled patch points during syncPatchDisplacement.
shrinkMeshMedialDistance : Smoothing using Medial Axis ...
shrinkMeshMedialDistance : Reduce layer thickness at 0 nodes where thickness to medial axis distance is large
shrinkMeshDistance : Removing isolated regions ...
Number isolated points extrusion stopped : 9
shrinkMeshDistance : Smoothing field ...
Iteration 0 residual 0.00104
shrinkMeshMedialDistance : Moving mesh ...
Iteration 0
Moving mesh using diplacement scaling : min:1 max:1
Checking faces in error :
faces with face pyramid volume < 1e13 : 0
faces with facedecomposition tet quality < 1e30 : 0
faces with skewness > 4 (internal) or 20 (boundary) : 0
faces with interpolation weights (0..1) < 0.02 : 0
faces with volume ratio of neighbour cells < 0.01 : 0
faces with face twist < 0.02 : 0
faces on cells with determinant < 0.001 : 0
shrinkMeshMedialDistance : Successfully moved mesh
shrinkMeshMedialDistance : Finished moving mesh ...
Prevented extrusion on 0 coupled patch points during syncPatchDisplacement.
truncateDisplacement : Unextruded 0 faces due to nonconsecutive vertices being extruded.
truncateDisplacement : Unextruded 0 faces due to stringed edges with inconsistent extrusion.
Setting up information for layer truncation ...
Checking mesh with layer ...
Checking faces in error :
faces with face pyramid volume < 1e13 : 0
faces with facedecomposition tet quality < 1e30 : 0
faces with skewness > 4 (internal) or 20 (boundary) : 0
faces with interpolation weights (0..1) < 0.02 : 0
faces with volume ratio of neighbour cells < 0.01 : 0
faces with face twist < 0.02 : 0
faces on cells with determinant < 0.001 : 0
Detected 0 illegal faces (concave, zero area or negative cell pyramid volume)
Extruding 3736 out of 4536 faces (82.4%). Removed extrusion at 0 faces.
Edge intersection testing:
Number of edges : 339036
Number of edges to retest : 0
Number of intersected edges : 60289
Writing 55752 added cells to cellSet addedCells
Writing 52016 faces inside added layer to faceSet layerFaces
Layer mesh : cells:109064 faces:339036 points:121291
Cells per refinement level:
0 7568
1 2456
2 6988
3 7552
4 2780
5 8004
6 73716
Writing mesh to time 3e07
Wrote mesh in = 5.26 s.
Layers added in = 5.26 s.
Finished meshing in = 12.6 s.
End
