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[mesh manipulation] tetrahedral to polyhedral mesh conversion failed

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Old   March 9, 2022, 15:59
Default tetrahedral to polyhedral mesh conversion failed
  #1
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Marko Josic
Join Date: Dec 2010
Posts: 20
Rep Power: 13
emjay is on a distinguished road
Hello Community,

I have created a simple tetrahedral mesh and for me it is not possible to convert it to polyhedral mesh. I studied the documentation but I could not find the true configuration.

or, how could I merge the hexahedral elements to a polyhedral element?



Code:
fluent3DMeshToFoam test.msh
polyDualMesh 135
combinePatchFaces 75
checkMesh gives me for the imported grid:
Code:
/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  dev
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
Build  : dev-1bbbd40a0d4e
Exec   : checkMesh -time 0
Date   : Mar 09 2022
Time   : 20:44:06
Host   : "ee4e6c8cc759"
PID    : 264
I/O    : uncollated
Case   : /home/openfoam/test
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
    points:           1274
    faces:            12390
    internal faces:   11502
    cells:            5973
    faces per cell:   4
    boundary patches: 1
    point zones:      0
    face zones:       1
    cell zones:       1

Overall number of cells of each type:
    hexahedra:     0
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    5973
    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                  
    wall_0              888      446      ok (closed singly connected)      

Checking geometry...
    Overall domain bounding box (-1 -0.866025 -0.5) (1 0.866025 0.5)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (-2.58749e-17 1.42544e-17 3.74953e-17) OK.
    Max cell openness = 2.17769e-16 OK.
    Max aspect ratio = 4.48391 OK.
    Minimum face area = 0.00171147. Maximum face area = 0.0426597.  Face area magnitudes OK.
    Min volume = 4.1545e-05. Max volume = 0.0026691.  Total volume = 2.59808.  Cell volumes OK.
    Mesh non-orthogonality Max: 51.3143 average: 20.0735
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.467139 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End
and for the "polyhedral mesh":
Code:
/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  dev
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
Build  : dev-1bbbd40a0d4e
Exec   : checkMesh -time 1
Date   : Mar 09 2022
Time   : 20:44:48
Host   : "ee4e6c8cc759"
PID    : 265
I/O    : uncollated
Case   : /home/openfoam/test
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create polyMesh for time = 1

Time = 1

Mesh stats
    points:           27327
    faces:            73008
    internal faces:   70344
    cells:            23892
    faces per cell:   6
    boundary patches: 1
    point zones:      0
    face zones:       1
    cell zones:       1

Overall number of cells of each type:
    hexahedra:     23892
    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                  
    wall_0              2664     2666     ok (closed singly connected)      

Checking geometry...
    Overall domain bounding box (-1 -0.866025 -0.5) (1 0.866025 0.5)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (8.34735e-17 1.58929e-16 1.57263e-17) OK.
    Max cell openness = 2.42594e-16 OK.
    Max aspect ratio = 4.69317 OK.
    Minimum face area = 0.00020238. Maximum face area = 0.0142199.  Face area magnitudes OK.
    Min volume = 1.03862e-05. Max volume = 0.000667274.  Total volume = 2.59808.  Cell volumes OK.
    Mesh non-orthogonality Max: 59.5439 average: 24.966
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.692838 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End

thank you
for your help
Attached Images
File Type: png tetrahedral.png (190.2 KB, 14 views)
File Type: jpg polyhedral.jpg (56.4 KB, 17 views)
Attached Files
File Type: zip test.msh.zip (112.5 KB, 3 views)
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Old   April 28, 2022, 10:22
Default
  #2
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Nicolas Nuņez Sandoval
Join Date: Aug 2017
Location: Chile, Latinoamerica
Posts: 2
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Marko, I add to your cause for a little help to solve this problem.
I try polyDualMesh with another basics geometries like cubes and cylinders without good visual results.

About your problem, I used your mesh and the problem is the same as yours: OpenFOAM turns tetrahedral to hexahedral elements.
So, I do the same geometry and mesh in Salome-Meca-2019-0.1, then apply your same steps and the result is different (see attached files)

With different mesher software the results are quite different. Obviously, that is a problem but I'm sure (and I hope) some another user can help us with this issue.

My initial geometry with tetrahedral elements:
Code:
Time = 0

Mesh stats
    points:           2431
    faces:            21706
    internal faces:   19058
    cells:            10191
    faces per cell:   4
    boundary patches: 1
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     0
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    10191
     polyhedra:     0
My final geometry with polyhedral elements:
Code:
Time = 0.005

Mesh stats
    points:           12839
    internal points:  10191
    faces:            15271
    internal faces:   13945
    cells:            2431
    faces per cell:   12.0181
    boundary patches: 1
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     5
    prisms:        6
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     2420
Attached Images
File Type: jpg tetra.jpg (51.6 KB, 5 views)
File Type: jpg polyH.jpg (51.5 KB, 6 views)
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Old   May 2, 2022, 09:49
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  #3
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Nicolas Nuņez Sandoval
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Hey! I found a solution for the polyhedral visualization.
Paraview/Properties/"toogle advanced properties"/(unclick) Decompose polyhedra, "apply" and ready!


Credits: https://discourse.paraview.org/t/dec...in-v5-8-0/4327


Until now I don't have any answer for the unexpected transformation from tetra to hexa doing polyDualMesh with Fluent mesh.
Attached Images
File Type: png polyhedral-visualization-solution.png (165.3 KB, 8 views)
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