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Wrong results with imported mesh

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Old   May 1, 2018, 06:19
Default Wrong results with imported mesh
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Hi dear Foamers,

I am trying to do a simple pipe flow simulation using OpenFOAM with different mesh generators (blockMesh, ANSYS Meshing, gmsh). With blockMesh, I have good results.

However, when I am using the mesh from ANSYS or gmsh, the results are really weird. In both cases, the mesh is successfully converted and the job is solved (with simpleFoam). But when I have a look to the results, it is like there is no simulation since the velocity or pressure fields remain equal to zero (except at the boundaries - inlet, outlet, wall - where they are as implemented in the 0 directory).

I would like to mention that the file structure is the same in those 3 cases and I have checked that the polyMesh/boundary file is correctly setting the inlet, outlet and wall.

Can anyone help me figure it out ?

Thanks!
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Old   May 1, 2018, 06:24
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It looks if there are problems with exporting the boundary conditions. Did you run checkMesh?
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Old   May 1, 2018, 06:43
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Yes, I did (see below), it seems fair to me but I guess I am missing something.

Mesh stats
points: 370644
faces: 1092405
internal faces: 1073595
cells: 361000
faces per cell: 6
boundary patches: 3
point zones: 0
face zones: 0
cell zones: 1

Overall number of cells of each type:
hexahedra: 361000
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 1805 1844 ok (non-closed singly connected)
outlet 1805 1844 ok (non-closed singly connected)
wall 15200 15276 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (-0.0646247 -0.0646247 0) (0.0646247 0.0646247 6.4)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (-7.90514e-18 7.2137e-18 -5.12196e-18) OK.
Max cell openness = 2.14276e-16 OK.
Max aspect ratio = 35.1234 OK.
Minimum face area = 3.28961e-06. Maximum face area = 0.000171067. Face area magnitudes OK.
Min volume = 1.05268e-07. Max volume = 3.70513e-07. Total volume = 0.0840185. Cell volumes OK.
Mesh non-orthogonality Max: 37.47 average: 7.29246
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 0.982861 OK.
Coupled point location match (average 0) OK.

Mesh OK.
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Old   May 2, 2018, 08:39
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So the problem was that the coordinate system (from the ANSYS or gmsh mesh) was not the same as the one in blockMesh. As I kept the same 0/ files in the 3 cases, that is why my results were wrong.
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