| GianF |
November 16, 2017 07:52 |
Help with Snappy: no layers growing
Hi all, first time posting on forums but an avid reader :D
I have been trying to get layers to grow on a wing that is not perfectly aligned with the background mesh (created with blockMesh). I have been successful in the past when the wing was perpendicular to the part but cannot get it to work in this case.
I have attached my snappyHexMeshDict and snappyHexMesh report below. Any help is really appreciated.
As I understand it it seems that edge intersection testing is the main reason the thing isn't working but I could be wrong as i am pretty new to snappy
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: dev |
| \\ / 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
{
Hor.stl
{
type triSurfaceMesh;
name Hor;
}
};
// 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 false;
// Per final patch (so not geometry!) the layer information
layers
{
"(Hor).*"
{
nSurfaceLayers 1;
}
}
// Expansion factor for layer mesh
expansionRatio 1.3;
// 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 0.001;
// 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.
minThickness 0.01;
// 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 1;
// Advanced settings
// When not to extrude surface. 0 is flat surface, 90 is when two faces
// are perpendicular
featureAngle 60;
// 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 30;
// 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
// Note: changed(corrected) w.r.t 17x! 90 degrees corresponds to 130 in 17x.
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 150;
}
// Generic mesh quality settings. At any undoable phase these determine
// where to undo.
meshQualityControls
{
#include "meshQualityDict"
// Advanced
//- Number of error distribution iterations
nSmoothScale 8;
//- Amount to scale back displacement at error points
errorReduction 0.5;
}
// Advanced
// Write flags
writeFlags
(
scalarLevels
layerSets
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-6;
// ************************************************************************* //
Code:
Shrinking and layer addition phase
----------------------------------
Using mesh parameters
{
maxNonOrtho 70;
maxBoundarySkewness 20;
maxInternalSkewness 4;
maxConcave 80;
minVol 1e-013;
minTetQuality 1e-015;
minArea -1;
minTwist 0.02;
minDeterminant 0.005;
minFaceWeight 0.02;
minVolRatio 0.01;
minTriangleTwist -1;
nSmoothScale 8;
errorReduction 0.5;
}
Merging all faces of a cell
---------------------------
- which are on the same patch
- which make an angle < 60 degrees
(cos:0.5)
- as long as the resulting face doesn't become concave by more than 90 degrees
(0=straight, 180=fully concave)
Merging 3555 sets of faces.
Edge intersection testing:
Number of edges : 3786657
Number of edges to retest : 19959
Number of intersected edges : 165712
Undo iteration 0
----------------
Checking faces in error :
non-orthogonality > 70 degrees : 42
faces with face pyramid volume < 1e-013 : 0
faces with face-decomposition tet quality < 1e-015 : 18
faces with concavity > 80 degrees : 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 < 0.005 : 8
Masters that need to be restored:76
Edge intersection testing:
Number of edges : 3786825
Number of edges to retest : 757
Number of intersected edges : 165880
Undo iteration 1
----------------
Checking faces in error :
non-orthogonality > 70 degrees : 0
faces with face pyramid volume < 1e-013 : 0
faces with face-decomposition tet quality < 1e-015 : 0
faces with concavity > 80 degrees : 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 < 0.005 : 0
Merging all points on surface that
- are used by only two boundary faces and
- make an angle with a cosine of more than 0.5.
Removing 3913 straight edge points ...
Edge intersection testing:
Number of edges : 3786825
Number of edges to retest : 29893
Number of intersected edges : 165880
Undo iteration 0
----------------
Checking faces in error :
non-orthogonality > 70 degrees : 6
faces with face pyramid volume < 1e-013 : 0
faces with face-decomposition tet quality < 1e-015 : 0
faces with concavity > 80 degrees : 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 < 0.005 : 0
Detected 4 error faces on boundaries that have been merged. These will be restored to their original faces.
Edge intersection testing:
Number of edges : 3786825
Number of edges to retest : 46
Number of intersected edges : 165880
Undo iteration 1
----------------
Checking faces in error :
non-orthogonality > 70 degrees : 2
faces with face pyramid volume < 1e-013 : 0
faces with face-decomposition tet quality < 1e-015 : 1
faces with concavity > 80 degrees : 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 < 0.005 : 0
Detected 0 error faces on boundaries that have been merged. These will be restored to their original faces.
Detected 3 error faces in mesh. Restoring neighbours of faces in error.
Edge intersection testing:
Number of edges : 3786825
Number of edges to retest : 124
Number of intersected edges : 165880
Checking mesh manifoldness ...
Checking initial mesh ...
Checking faces in error :
non-orthogonality > 70 degrees : 0
faces with face pyramid volume < 1e-013 : 0
faces with face-decomposition tet quality < 1e-015 : 0
faces with concavity > 80 degrees : 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 < 0.005 : 0
Detected 0 illegal faces (concave, zero area or negative cell pyramid volume)
Adding in total 0 inter-processor patches to handle extrusion of non-manifold processor boundaries.
Handling points with inconsistent layer specification ...
Handling non-manifold 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 non-manifold points
Handling feature edges ...
Growing non-extrusion points by one layer ...
Set displacement to zero for an additional 0 points.
patch faces layers avg thickness[m]
near-wall overall
----- ----- ------ --------- -------
motorBike 166049 1 0.001 0.001
Selecting externalDisplacementMeshMover displacementMedialAxis
displacementMedialAxis : Calculating distance to Medial Axis ...
displacementMedialAxis : Smoothing normals ...
Iteration 0 residual 0.0147636
displacementMedialAxis : Inserting points on patch atmosphere if angle to nearest layer patch > 30 degrees.
displacementMedialAxis : Inserting points on patch outlet if angle to nearest layer patch > 30 degrees.
displacementMedialAxis : Inserting points on patch inlet if angle to nearest layer patch > 30 degrees.
displacementMedialAxis : Inserting points on patch bottom if angle to nearest layer patch > 30 degrees.
displacementMedialAxis : Inserting points on patch side if angle to nearest layer patch > 30 degrees.
displacementMedialAxis : Inserting points on patch midPlane if angle to nearest layer patch > 30 degrees.
displacementMedialAxis : Smoothing normals in interior ...
Iteration 0 residual 0.039521
Layer addition iteration 0
--------------------------
Determining displacement for added points according to pointNormal ...
Detected 886 points with point normal pointing through faces.
Reset displacement at 886 points to average of surrounding points.
displacementMedialAxis : Smoothing using Medial Axis ...
displacementMedialAxis : Reducing layer thickness at 0 nodes where thickness to medial axis distance is large
displacementMedialAxis : Removing isolated regions ...
displacementMedialAxis : Number of isolated points extrusion stopped : 0
displacementMedialAxis : Smoothing field ...
Iteration 0 residual 0
displacementMedialAxis : Moving mesh ...
displacementMedialAxis : Iteration 0
Moving mesh using displacement scaling : min:1 max:1
Checking faces in error :
non-orthogonality > 70 degrees : 0
faces with face pyramid volume < 1e-013 : 0
faces with face-decomposition tet quality < 1e-015 : 0
faces with concavity > 80 degrees : 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 < 0.005 : 0
displacementMedialAxis : Successfully moved mesh
displacementMedialAxis : Finished moving mesh ...
truncateDisplacement : Unextruded 0 faces due to non-consecutive 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 :
non-orthogonality > 70 degrees : 0
faces with face pyramid volume < 1e-013 : 0
faces with face-decomposition tet quality < 1e-015 : 0
faces with concavity > 80 degrees : 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 < 0.005 : 0
Detected 0 illegal faces (concave, zero area or negative cell pyramid volume)
Extruding 0 out of 166049 faces (0%). Removed extrusion at 0 faces.
Added 0 out of 166049 cells (0%).
Edge intersection testing:
Number of edges : 3786825
Number of edges to retest : 0
Number of intersected edges : 165880
Doing final balancing
---------------------
Writing 0 added cells to cellSet addedCells
Writing 0 faces inside added layer to faceSet layerFaces
Writing fields with layer information:
nSurfaceLayers : actual number of layers
thickness : overall layer thickness
thicknessFraction : overall layer thickness (fraction of desired thickness)
patch faces layers overall thickness
[m] [%]
----- ----- ------ --- ---
motorBike 166049 0 0 0
Layer mesh : cells:1188561 faces:3786825 points:1437885
Cells per refinement level:
0 239693
1 5384
2 12869
3 36171
4 116321
5 480434
6 297689
Writing mesh to time constant
Wrote mesh in = 20.108 s.
Layers added in = 20.108 s.
Checking final mesh ...
Checking faces in error :
non-orthogonality > 70 degrees : 0
faces with face pyramid volume < 1e-013 : 0
faces with face-decomposition tet quality < 1e-015 : 0
faces with concavity > 80 degrees : 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 < 0.005 : 0
Finished meshing without any errors
Finished meshing in = 547.434 s.
End
Finalising parallel run
Any help is really appreciated
PS:
I am currently downloading Salome and will try to see if improving my stl will make a difference. |
