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March 16, 2017, 16:09 
cfMesh questions

#1 
Member
badoumba
Join Date: Aug 2013
Posts: 61
Rep Power: 6 
Hi everyone!
I have a bunch of questions regarding cfMesh, if anyone has any input for me.  for external aerodynamics, I am starting with a stl file consisting of the object to study that I put within a box. Can we use cfMesh in combination with blockMesh so I just need a stl file with my object instead? I tried by running blockMesh first and then cartesianLMesh but at the end paraFoam opens only the initial blockMesh mesh and not the cartesianMesh buit one.  The mesh seems cleaner than the one I had with sHM, but surprisingly checkMesh reports a lot of errors, especially negative volume (wichever untangleLayers boolean value set), extremely high ratio cells and number of edges not aligned with or perpendicular to nonempty directions. Is there any quality control system coupled?  If I don't need especially low y+ and decide to go for a coarser mesh, it turns out to be very irregular at some sharp or curved parts. It seems that there is no "snapping" like in sHM (surfaceProjection but not exactly the same end result) o we have cells not fitting perfectly the surface which has an impact on any final visual. Only solution is to go for finer resolution. Any feedback regarding this point? Can we apply a sHM snapping step on top of a cfMesh (I know that for cartesian Mesh there is a default layer, might be a problem).  Is there any diagnosis tool like layer coverture ? Thanks guys ! Last edited by badoumba; March 17, 2017 at 03:10. 

March 17, 2017, 04:29 

#2 
Member
badoumba
Join Date: Aug 2013
Posts: 61
Rep Power: 6 
Regarding the second point, here is the detail of the errors I had so far.
To be sure, I initially run a surfaceCheck on my stl object, reporting no errors. Below are the cfMesh steps in sequence and the corresponding checkMesh report. Despite of my stl mesh being OK, I already have an error at first step Code:
***Faces not in upper triangular order. Almost fixed at the end but I still have Code:
***Number of edges not aligned with or perpendicular to nonempty directions Code:
Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. ***Faces not in upper triangular order. <<Writing 254379 unordered faces to set upperTriangularFace Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology defaultFaces 132282 131761 multiply connected (shared edge) <<Writing 785 conflicting points to set nonManifoldPoints Checking geometry... Overall domain bounding box (2.6 1.83559 2) (2.6 3.76441 2) Mesh has 3 geometric (nonempty/wedge) directions (1 1 1) Mesh has 3 solution (nonempty) directions (1 1 1) Boundary openness (3.09535e16 6.5087e15 4.18046e14) OK. Max cell openness = 3.46945e16 OK. Max aspect ratio = 1 OK. Minimum face area = 3.90625e05. Maximum face area = 0.04. Face area magnitudes OK. Min volume = 2.44141e07. Max volume = 0.008. Total volume = 116.277. Cell volumes OK. Mesh nonorthogonality Max: 25.2394 average: 9.8424 Nonorthogonality check OK. Face pyramids OK. Max skewness = 0.333333 OK. Coupled point location match (average 0) OK. Failed 1 mesh checks. Code:
Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. ***Faces not in upper triangular order. <<Writing 253870 unordered faces to set upperTriangularFace Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology defaultFaces 129678 129662 ok (closed singly connected) Checking geometry... Overall domain bounding box (2.6 1.83559 2) (2.6 3.76441 2) Mesh has 3 geometric (nonempty/wedge) directions (1 1 1) Mesh has 3 solution (nonempty) directions (1 1 1) Boundary openness (3.09745e16 7.2506e15 4.1341e14) OK. Max cell openness = 3.46945e16 OK. Max aspect ratio = 1 OK. Minimum face area = 3.90625e05. Maximum face area = 0.04. Face area magnitudes OK. Min volume = 2.44141e07. Max volume = 0.008. Total volume = 116.277. Cell volumes OK. Mesh nonorthogonality Max: 25.2394 average: 9.85378 Nonorthogonality check OK. Face pyramids OK. Max skewness = 0.333333 OK. Coupled point location match (average 0) OK. Failed 1 mesh checks. Code:
Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. ***Faces not in upper triangular order. <<Writing 253870 unordered faces to set upperTriangularFace Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology defaultFaces 129678 129662 ok (closed singly connected) Checking geometry... Overall domain bounding box (2.6 1.83559 2) (2.6 3.76441 2) Mesh has 3 geometric (nonempty/wedge) directions (1 1 1) Mesh has 3 solution (nonempty) directions (1 1 1) Boundary openness (3.57253e16 7.31184e15 4.13817e14) OK. Max cell openness = 3.46945e16 OK. Max aspect ratio = 1 OK. Minimum face area = 3.90625e05. Maximum face area = 0.04. Face area magnitudes OK. Min volume = 2.44141e07. Max volume = 0.008. Total volume = 116.277. Cell volumes OK. Mesh nonorthogonality Max: 25.2394 average: 9.85378 Nonorthogonality check OK. Face pyramids OK. Max skewness = 0.333333 OK. Coupled point location match (average 0) OK. Failed 1 mesh checks. Code:
Checking topology... Boundary definition OK. ***Total number of faces on empty patches is not divisible by the number of cells in the mesh. Hence this mesh is not 1D or 2D. Cell to face addressing OK. Point usage OK. ***Faces not in upper triangular order. <<Writing 253870 unordered faces to set upperTriangularFace Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology inlet 520 567 ok (nonclosed singly connected) outlet 520 567 ok (nonclosed singly connected) top 728 783 ok (nonclosed singly connected) bottom 728 783 ok (nonclosed singly connected) left 560 609 ok (nonclosed singly connected) right 560 609 ok (nonclosed singly connected) ws 126062 126044 ok (closed singly connected) Checking geometry... Overall domain bounding box (2.48853 1.64886 1.91) (2.48853 3.57767 1.91) Mesh has 0 geometric (nonempty/wedge) directions (0 0 0) Mesh has 0 solution (nonempty) directions (0 0 0) ***Number of edges not aligned with or perpendicular to nonempty directions: 383367 <<Writing 211533 points on nonaligned edges to set nonAlignedEdges Boundary openness (1.10492e16 5.47885e16 3.57502e16) OK. Max cell openness = 9.79989e16 OK. Max aspect ratio = 1 OK. Minimum face area = 6.03942e08. Maximum face area = 0.04. Face area magnitudes OK. ***Zero or negative cell volume detected. Minimum negative volume: 3.50553e08, Number of negative volume cells: 428 <<Writing 428 zero volume cells to set zeroVolumeCells Mesh nonorthogonality Max: 179.732 average: 17.4551 *Number of severely nonorthogonal (> 70 degrees) faces: 14193. ***Number of nonorthogonality errors: 249. <<Writing 14442 nonorthogonal faces to set nonOrthoFaces ***Error in face pyramids: 6792 faces are incorrectly oriented. <<Writing 6702 faces with incorrect orientation to set wrongOrientedFaces ***Max skewness = 391.705, 806 highly skew faces detected which may impair the quality of the results <<Writing 806 skew faces to set skewFaces Coupled point location match (average 0) OK. Failed 6 mesh checks. Code:
Checking topology... Boundary definition OK. ***Total number of faces on empty patches is not divisible by the number of cells in the mesh. Hence this mesh is not 1D or 2D. Cell to face addressing OK. Point usage OK. ***Faces not in upper triangular order. <<Writing 253870 unordered faces to set upperTriangularFace Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology inlet 520 567 ok (nonclosed singly connected) outlet 520 567 ok (nonclosed singly connected) top 728 783 ok (nonclosed singly connected) bottom 728 783 ok (nonclosed singly connected) left 560 609 ok (nonclosed singly connected) right 560 609 ok (nonclosed singly connected) ws 126062 126044 ok (closed singly connected) Checking geometry... Overall domain bounding box (2.48853 1.64886 1.91) (2.48853 3.57767 1.91) Mesh has 0 geometric (nonempty/wedge) directions (0 0 0) Mesh has 0 solution (nonempty) directions (0 0 0) ***Number of edges not aligned with or perpendicular to nonempty directions: 390796 <<Writing 216335 points on nonaligned edges to set nonAlignedEdges Boundary openness (2.16088e16 1.9379e16 1.6233e16) OK. Max cell openness = 1.19107e15 OK. Max aspect ratio = 1 OK. Minimum face area = 2.86707e08. Maximum face area = 0.0400005. Face area magnitudes OK. ***Zero or negative cell volume detected. Minimum negative volume: 2.92435e08, Number of negative volume cells: 388 <<Writing 388 zero volume cells to set zeroVolumeCells Mesh nonorthogonality Max: 179.309 average: 17.6868 *Number of severely nonorthogonal (> 70 degrees) faces: 15224. ***Number of nonorthogonality errors: 293. <<Writing 15517 nonorthogonal faces to set nonOrthoFaces ***Error in face pyramids: 6619 faces are incorrectly oriented. <<Writing 6564 faces with incorrect orientation to set wrongOrientedFaces ***Max skewness = 4472.82, 803 highly skew faces detected which may impair the quality of the results <<Writing 803 skew faces to set skewFaces Coupled point location match (average 0) OK. Failed 6 mesh checks. Code:
Checking topology... Boundary definition OK. ***Total number of faces on empty patches is not divisible by the number of cells in the mesh. Hence this mesh is not 1D or 2D. Cell to face addressing OK. Point usage OK. ***Faces not in upper triangular order. <<Writing 320421 unordered faces to set upperTriangularFace Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology inlet 616 667 ok (nonclosed singly connected) outlet 616 667 ok (nonclosed singly connected) top 840 899 ok (nonclosed singly connected) bottom 840 899 ok (nonclosed singly connected) left 660 713 ok (nonclosed singly connected) right 660 713 ok (nonclosed singly connected) ws 126062 126044 ok (closed singly connected) Checking geometry... Overall domain bounding box (2.48853 1.64886 1.91) (2.48853 3.57767 1.91) Mesh has 0 geometric (nonempty/wedge) directions (0 0 0) Mesh has 0 solution (nonempty) directions (0 0 0) ***Number of edges not aligned with or perpendicular to nonempty directions: 775711 <<Writing 346064 points on nonaligned edges to set nonAlignedEdges Boundary openness (1.90407e16 4.27573e16 5.45906e17) OK. Max cell openness = 3.07327e15 OK. Max aspect ratio = 1 OK. Minimum face area = 4.9538e09. Maximum face area = 0.0400005. Face area magnitudes OK. ***Zero or negative cell volume detected. Minimum negative volume: 0.00346874, Number of negative volume cells: 42662 <<Writing 42662 zero volume cells to set zeroVolumeCells Mesh nonorthogonality Max: 180 average: 32.083 *Number of severely nonorthogonal (> 70 degrees) faces: 78889. ***Number of nonorthogonality errors: 75956. <<Writing 154845 nonorthogonal faces to set nonOrthoFaces ***Error in face pyramids: 262224 faces are incorrectly oriented. <<Writing 199176 faces with incorrect orientation to set wrongOrientedFaces ***Max skewness = 38434.2, 9959 highly skew faces detected which may impair the quality of the results <<Writing 9959 skew faces to set skewFaces Coupled point location match (average 0) OK. Failed 6 mesh checks. Code:
Checking topology... Boundary definition OK. ***Total number of faces on empty patches is not divisible by the number of cells in the mesh. Hence this mesh is not 1D or 2D. Cell to face addressing OK. Point usage OK. ***Faces not in upper triangular order. <<Writing 320421 unordered faces to set upperTriangularFace Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology inlet 616 667 ok (nonclosed singly connected) outlet 616 667 ok (nonclosed singly connected) top 840 899 ok (nonclosed singly connected) bottom 840 899 ok (nonclosed singly connected) left 660 713 ok (nonclosed singly connected) right 660 713 ok (nonclosed singly connected) ws 126062 126044 ok (closed singly connected) Checking geometry... Overall domain bounding box (2.48853 1.64886 1.91) (2.48853 3.57767 1.91) Mesh has 0 geometric (nonempty/wedge) directions (0 0 0) Mesh has 0 solution (nonempty) directions (0 0 0) ***Number of edges not aligned with or perpendicular to nonempty directions: 1890761 <<Writing 677021 points on nonaligned edges to set nonAlignedEdges Boundary openness (3.5724e17 8.48847e17 1.1956e16) OK. Max cell openness = 4.10648e16 OK. Max aspect ratio = 1 OK. Minimum face area = 6.69045e07. Maximum face area = 0.0412546. Face area magnitudes OK. Min volume = 1.15326e09. Max volume = 0.00883498. Total volume = 99.1529. Cell volumes OK. Mesh nonorthogonality Max: 81.2189 average: 13.6253 *Number of severely nonorthogonal (> 70 degrees) faces: 169. Nonorthogonality check OK. <<Writing 169 nonorthogonal faces to set nonOrthoFaces Face pyramids OK. Max skewness = 2.78854 OK. Coupled point location match (average 0) OK. Failed 2 mesh checks. Code:
Checking topology... Boundary definition OK. ***Total number of faces on empty patches is not divisible by the number of cells in the mesh. Hence this mesh is not 1D or 2D. 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 616 667 ok (nonclosed singly connected) outlet 616 667 ok (nonclosed singly connected) top 840 899 ok (nonclosed singly connected) bottom 840 899 ok (nonclosed singly connected) left 660 713 ok (nonclosed singly connected) right 660 713 ok (nonclosed singly connected) ws 126062 126044 ok (closed singly connected) Checking geometry... Overall domain bounding box (2.48853 1.64886 1.91) (2.48853 3.57767 1.91) Mesh has 0 geometric (nonempty/wedge) directions (0 0 0) Mesh has 0 solution (nonempty) directions (0 0 0) ***Number of edges not aligned with or perpendicular to nonempty directions: 1890763 <<Writing 677019 points on nonaligned edges to set nonAlignedEdges Boundary openness (2.50854e17 1.33239e16 1.45375e16) OK. Max cell openness = 3.29611e16 OK. Max aspect ratio = 1 OK. Minimum face area = 6.74561e07. Maximum face area = 0.0412546. Face area magnitudes OK. Min volume = 2.91116e09. Max volume = 0.00883498. Total volume = 99.1529. Cell volumes OK. Mesh nonorthogonality Max: 69.883 average: 13.0992 Nonorthogonality check OK. Face pyramids OK. Max skewness = 2.6205 OK. Coupled point location match (average 0) OK. Failed 1 mesh checks. 

March 17, 2017, 04:40 

#3 
Member
badoumba
Join Date: Aug 2013
Posts: 61
Rep Power: 6 
Regarding the third point, here is a screenshot of what I am refering to.
In white is my edges.vtk Thanks 

March 17, 2017, 04:46 

#4 
Member
badoumba
Join Date: Aug 2013
Posts: 61
Rep Power: 6 
And for the first point (sorry not being in order), my concern is how to set a symmetry patch in a model with cfMesh. Did'nt find any related tutorial or procedure.
Should I force my side mesh to Symmetry type in renameBoundary dictionnary? Sorry to spam, I'm done update : Answering my own question, sharing it Wall symmetry is implemented as following: renameBoundary { newPatchNames { right { newName symmetry_plane; type symmetry; } } } Last edited by badoumba; March 17, 2017 at 07:22. 

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