| aerospacious |
August 20, 2018 05:08 |
cfMesh + extrudeMesh -> bad quality mesh?
Hey fellow foamers,
The reason for this post is because I am running into some problems when Extruding a mesh generated by cfMesh.
For some reason the quality of the cfMesh is fine and the checkMesh utility does not flag a single problem.
checkMesh result cfMesh:
Code:
Mesh stats
points: 18141991
faces: 52760636
internal faces: 51354113
cells: 17311300
faces per cell: 6.01427
boundary patches: 7
point zones: 0
face zones: 0
cell zones: 0
Overall number of cells of each type:
hexahedra: 17216033
prisms: 628
wedges: 0
pyramids: 1190
tet wedges: 0
tetrahedra: 492
polyhedra: 92957
Breakdown of polyhedra by number of faces:
faces number of cells
6 13448
7 14140
8 108
9 52169
12 12980
15 112
Checking topology...
Boundary definition OK.
Cell to face addressing OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK).
Checking patch topology for multiply connected surfaces...
Patch Faces Points Surface topology
inlet 486 652 ok (non-closed singly connected)
outlet 2008 2288 ok (non-closed singly connected)
front 671323 675329 ok (non-closed singly connected)
back 684354 688365 ok (non-closed singly connected)
top 966 1292 ok (non-closed singly connected)
bottom 966 1292 ok (non-closed singly connected)
marlyn 46420 47106 ok (non-closed singly connected)
Checking geometry...
Overall domain bounding box (-5.3 -0.4 -4) (10.7 -0.299998 4)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (1.74977e-18 3.67367e-13 4.64238e-17) OK.
Max cell openness = 7.56747e-16 OK.
Max aspect ratio = 36.5897 OK.
Minimum face area = 7.09395e-09. Maximum face area = 0.00273625. Face area magnitudes OK.
Min volume = 2.33909e-12. Max volume = 0.000108415. Total volume = 12.7988. Cell volumes OK.
Mesh non-orthogonality Max: 61.8058 average: 1.46265
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 1.73461 OK.
Coupled point location match (average 0) OK.
Mesh OK.
However, when I run extrudeMesh from a patch created by cfMesh it does (not so) funny things.
checkMesh result cfMesh + extrudeMesh:
Code:
Mesh stats
points: 1376730
internal points: 0
faces: 2741427
internal faces: 1371010
cells: 684354
faces per cell: 6.00922
boundary patches: 7
point zones: 0
face zones: 0
cell zones: 0
Overall number of cells of each type:
hexahedra: 677647
prisms: 224
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 6483
Breakdown of polyhedra by number of faces:
faces number of cells
7 6429
8 54
Checking topology...
Boundary definition OK.
Cell to face addressing OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK).
Checking patch topology for multiply connected surfaces...
Patch Faces Points Surface topology
inlet 162 326 ok (non-closed singly connected)
outlet 274 550 ok (non-closed singly connected)
front 684354 688365 ok (non-closed singly connected)
back 684354 688365 ok (non-closed singly connected)
top 322 646 ok (non-closed singly connected)
bottom 322 646 ok (non-closed singly connected)
marlyn 629 1258 ok (non-closed singly connected)
Checking geometry...
Overall domain bounding box (-5.3 -0.3 -4) (10.7 0.700002 4)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (-1.40344e-17 1.69986e-13 9.9365e-17) OK.
***High aspect ratio cells found, Max aspect ratio: 1.33419e+97, number of cells 7102
<<Writing 7102 cells with high aspect ratio to set highAspectRatioCells
Minimum face area = 7.3062e-09. Maximum face area = 0.0529325. Face area magnitudes OK.
***Zero or negative cell volume detected. Minimum negative volume: -1.7993e-06, Number of negative volume cells: 8
<<Writing 8 zero volume cells to set zeroVolumeCells
Mesh non-orthogonality Max: 162.379 average: 1.08717
*Number of severely non-orthogonal (> 70 degrees) faces: 72.
***Number of non-orthogonality errors: 17.
<<Writing 89 non-orthogonal faces to set nonOrthoFaces
***Error in face pyramids: 40 faces are incorrectly oriented.
<<Writing 35 faces with incorrect orientation to set wrongOrientedFaces
***Max skewness = 35.2287, 3 highly skew faces detected which may impair the quality of the results
<<Writing 3 skew faces to set skewFaces
Coupled point location match (average 0) OK.
Failed 5 mesh checks.
End
Oddly enough I don think I am doing something weird with the extrudeMeshDict either. Though I encountered some problems before when the merge tolerance was too low resulting in collapsed edges, this is not happening in the current situation.
Furthermore, not all meshes that I have created with cfMesh experienced these kind of problems with extrudeMesh so I am at a loss.
extrudeMeshDict:
Code:
constructFrom patch;
sourceCase ".";
sourcePatches (front);
exposedPatchName back;
flipNormals false;
nLayers 1;
expansionRatio 1;
extrudeModel linearNormal;
linearNormalCoeffs
{
thickness 1;
}
mergeFaces false;
mergeTol 1e-8;
extrudeMesh log:
Code:
Create mesh for time = 0
Selecting extrudeModel linearNormal
Extruding from patch using model linearNormal
Collapsing edges < 1e-08 of bounding box
Extruding patches 1(front) on mesh "/mnt/homedirs/timo.vanpelt/OpenFOAM/timo.vanpelt-5.0/run/cavity/with_cavity/AoA-X/AoA8_r"
Create mesh for time = 0
Adding overall 0 processor patches.
Testing:"/mnt/homedirs/timo.vanpelt/OpenFOAM/timo.vanpelt-5.0/run/cavity/with_cavity/AoA-X/AoA8_r/system/fvSchemes"
Mesh bounding box : (-5.3 -1.4 -4) (10.7 -0.4 4)
with span : (16 1 8)
Merge distance : 1e-08
Collapsing edges < 1e-08 ...
Uncollapsed edges = 0 / 3368633
Number of points : 1350658
Not visited : 0
Not collapsed : 1350658
Collapsed : 0
Collapsing 0 cells
Writing mesh to "/mnt/homedirs/timo.vanpelt/OpenFOAM/timo.vanpelt-5.0/run/cavity/with_cavity/AoA-X/AoA8_r/constant/region0"
End
Has anyone encountered a similar problem and found a fix, it would be greatly appreciated :D |
