[faab]

Dear FOAMers,

The physics of the problem I am trying to solve is not useful to grasp the problem at hand here, as I am really struggling with the mesh only. I created a geometry on Gambit, starting from a 2D drawing, and then extruding all the faces 1 cell in the 3rd dimension to get a 3D mesh to use on OpenFOAM. After this I created my regions (fluids and solids) and of course defined the boundaries, I defined the "front and back" faces as internal/interior to later convert them into "empty" patches on OpenFOAM, from the polymesh folder.
When I export the mesh and run fluent3DtoFoam everything is fine and checkMesh shows that the mesh is built correctly. However, when I go into the boundary file of the constant/polymesh folder, and modify "patch" into "empty" for the front and back boundaries, I get a failed mesh statement {Number of edges not aligned with or perpendicular to non-empty directions: 1620}.
I have tried everything I could from the information I found on various forums, but nothing will do, if anyone has a suggestion this would be highly appreciated.
Thank you !

[faab]

I started the mesh from scratch and the problem was solved. Some issue resulting from a non-closed region most probably.

[ltiago94]

Hello,

I'm having this problem also, and tried everything I could.
What did you do exactly?

Thanks

Luís

[faab]

Hi,

Have you tried using the flattenMesh command ? If you get an error still, try expanding the mesh in the azimuthal direction with the transformPoints command first, and then use the flattenMesh. If this still doesn't work could you please paste the error message you get?

[ltiago94]

Hello,

how should I do that?

[ltiago94]

This is the message I'm getting with checkmesh

Create time

Create mesh for time = 0

Time = 0

Mesh stats
points: 221502
internal points: 0
faces: 440750
internal faces: 219250
cells: 110000
faces per cell: 6
boundary patches: 6
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 110000
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 0

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 200 402 ok (non-closed singly connected)
outlet 200 402 ok (non-closed singly connected)
bottomWall 550 1102 ok (non-closed singly connected)
top 550 1102 ok (non-closed singly connected)
front 110000 110751 ok (non-closed singly connected)
back 110000 110751 ok (non-closed singly connected)

Checking faceZone topology for multiply connected surfaces...
No faceZones found.

Checking basic cellZone addressing...
No cellZones found.

Checking geometry...
Overall domain bounding box (0 0 0) (18 0.4 0.9)
Mesh has 2 geometric (non-empty/wedge) directions (1 0 1)
Mesh has 2 solution (non-empty) directions (1 0 1)
All edges aligned with or perpendicular to non-empty directions.
Boundary openness (3.52959e-17 2.44305e-13 -1.77904e-15) OK.
Max cell openness = 9.20233e-17 OK.
Max aspect ratio = 7.27273 OK.
Minimum face area = 0.000147273. Maximum face area = 0.0130909. Face area magnitudes OK.
Min volume = 5.89091e-05. Max volume = 5.89091e-05. Total volume = 6.48. Cell volumes OK.
Mesh non-orthogonality Max: 0 average: 0
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 6.51331e-13 OK.
Coupled point location match (average 0) OK.

Mesh OK.

--> FOAM Warning :
From function virtual Foam:olyMesh::readUpdateState Foam:olyMesh::readUpdate()
in file meshes/polyMesh/polyMeshIO.C at line 209
unexpected consequences. Proceed with care.
Time = 0.001

Mesh stats
points: 579614
faces: 1283678
internal faces: 907363
cells: 353597
faces per cell: 6.19644
boundary patches: 7
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 330968
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 22629
Breakdown of polyhedra by number of faces:
faces number of cells
6 2023
9 18059
12 2547

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 200 402 ok (non-closed singly connected)
outlet 200 402 ok (non-closed singly connected)
bottomWall 775 1397 ok (non-closed singly connected)
top 550 1102 ok (non-closed singly connected)
front 153503 156600 ok (non-closed singly connected)
back 153503 156600 ok (non-closed singly connected)
ramp 67584 69729 ok (non-closed singly connected)

Checking faceZone topology for multiply connected surfaces...
No faceZones found.

Checking basic cellZone addressing...
No cellZones found.

Checking geometry...
Overall domain bounding box (0 0 0) (18 0.4 0.9)
Mesh has 2 geometric (non-empty/wedge) directions (1 0 1)
Mesh has 2 solution (non-empty) directions (1 0 1)
***Number of edges not aligned with or perpendicular to non-empty directions: 8020
<<Writing 13633 points on non-aligned edges to set nonAlignedEdges
Boundary openness (3.54341e-17 6.36221e-13 1.4412e-16) OK.
Max cell openness = 2.76808e-16 OK.
Max aspect ratio = 7.35714 OK.
Minimum face area = 1.428e-07. Maximum face area = 0.01312. Face area magnitudes OK.
Min volume = 1.785e-09. Max volume = 5.904e-05. Total volume = 6.47288. Cell volumes OK.
Mesh non-orthogonality Max: 88.0777 average: 23.1735
*Number of severely non-orthogonal (> 70 degrees) faces: 92612.
Non-orthogonality check OK.
<<Writing 92612 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
Max skewness = 0.336409 OK.
Coupled point location match (average 0) OK.

Failed 1 mesh checks.

Time = 0.002

Mesh stats
points: 571859
faces: 1276158
internal faces: 907363
cells: 353597
faces per cell: 6.17517
boundary patches: 7
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 323448
prisms: 7520
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 22629
Breakdown of polyhedra by number of faces:
faces number of cells
6 2023
9 18059
12 2547

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 200 402 ok (non-closed singly connected)
outlet 200 402 ok (non-closed singly connected)
bottomWall 775 1397 ok (non-closed singly connected)
top 550 1102 ok (non-closed singly connected)
front 153503 156365 ok (non-closed singly connected)
back 153503 156365 ok (non-closed singly connected)
ramp 60064 61974 ok (non-closed singly connected)

Checking faceZone topology for multiply connected surfaces...
No faceZones found.

Checking basic cellZone addressing...
No cellZones found.

Checking geometry...
Overall domain bounding box (0 0 0) (18 0.4 0.9)
Mesh has 2 geometric (non-empty/wedge) directions (1 0 1)
Mesh has 2 solution (non-empty) directions (1 0 1)
***Number of edges not aligned with or perpendicular to non-empty directions: 97190
<<Writing 137258 points on non-aligned edges to set nonAlignedEdges
Boundary openness (3.44952e-17 6.40669e-13 6.20785e-16) OK.
Max cell openness = 3.29873e-16 OK.
Max aspect ratio = 11.7111 OK.
Minimum face area = 6.3801e-08. Maximum face area = 0.01312. Face area magnitudes OK.
Min volume = 8.025e-10. Max volume = 5.904e-05. Total volume = 6.47287. Cell volumes OK.
Mesh non-orthogonality Max: 88.5063 average: 24.6622
*Number of severely non-orthogonal (> 70 degrees) faces: 92612.
Non-orthogonality check OK.
<<Writing 92612 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
***Max skewness = 5.46913, 4968 highly skew faces detected which may impair the quality of the results
<<Writing 4968 skew faces to set skewFaces
Coupled point location match (average 0) OK.

Failed 2 mesh checks.

End

[ltiago94]

i've also tried you suggestion and it didn't work

[faab]

I don't understand what you're doing exactly, you don't give enough information about your problem. Why do you run a checkMesh for Time 0.001, 0.002 ? The checkMesh for Time 0 is OK, so what did you do in between ?

[ltiago94]

My intend is to create a background mesh with block mesh. Then I need to include a geometry in the mesh which is doing fine. After that I run snapyhexmesh so it refines the mesh around the geometry and the free surface of the interface of water-air.
I thought that after running snappyhexmesh, I run the checkmesh utility, and that is the message I'm getting.

[faab]

I personally do not use snappyHexMesh (or only for "easy" single region mesh at times). However, although I understand the idea you still need to share the snappyHexMeshDict that you used, because I suspect that the issue may be coming from a wrong set up, and also share details about your geometry. Others, more familiar with the snappyHexMesh utility may then be able to guide you.

But I still don't understand why you are running a checkMesh on Times 0, 0.001 etc. From my understanding you should only have one 0 folder, and the constant folder containing the corresponding polymesh folder that you defined through blockMeshDict and after running snappyHexMesh. So why the Time 0.001, 0.002 in the checkMesh log ?

[ltiago94]

Originally Posted by faab

I personally do not use snappyHexMesh (or only for "easy" single region mesh at times). However, although I understand the idea you still need to share the snappyHexMeshDict that you used, because I suspect that the issue may be coming from a wrong set up, and also share details about your geometry. Others, more familiar with the snappyHexMesh utility may then be able to guide you.

But I still don't understand why you are running a checkMesh on Times 0, 0.001 etc. From my understanding you should only have one 0 folder, and the constant folder containing the corresponding polymesh folder that you defined through blockMeshDict and after running snappyHexMesh. So why the Time 0.001, 0.002 in the checkMesh log ?

I think that the time steps is related to the snappyhexmesh steps. 0.001s for castellated mesh and 0.002s for the snapping.
I attached the snappyhexmeshdict and my stl file.