[AlbertoArtoni]

I am trying to generate a polyhedral mesh.

1. I generate the tetrahedral mesh using TetGen
2. I import in OpenFoam and convert to OpenFoam format
3. I use polyDualMesh to convert to polyhedra

It seems to work all fine. I am making my tests on a cube and I am checking if the mesh works with checkMesh. It gives no issues.


Then I convert to VTK and post process it visually: I notice that some faces of my elements are not on a plane. For my application this is an important issue.


Also, I import them in matlab: I check the coplanarity of faces and the issue seem to be concrete, not some visual problem.


Is there a way I can fix it, generating polyhedral elements with planar faces?


I've already tried chaning polyDualMesh angle and using -concaveMultiCells options but the output doesn't change.


For instance, on a polyhedral cube mesh I can obtain the following statistics:
Of 4581 elements, at least 4529 have a non planar face.
Of 32002 faces, at least 18241 are not planar.






EDIT: I've added several zooms of differents mesh sizes.

[dolfus]

Hi,
I don't know if you fixed your probelm, but in case you haven't you can triangulate all mesh faces using the face geometric centre of the non planar faces. You can write some program in OF that reads the polyhedral mesh and writes a new one with cell faces triangulated in a new directory, e.g. constant/polyMesh.tri. Then just remove the old polyMesh and use the new one.
The structure of the program could be something like:
- Calculate face geometric centres for faces with more than 3 nodes. Append this points to the old file polyMesh/points.

- Loop over internal faces and create new triangular faces for each old face (assuming same owner and neighbour).
- Loop over all boundary faces and make same operations as in th previous step.
- Write polyMesh.tri/faces taking in account internal faces are first written and then all boundary ones starting from patch 0.
- Write the rest of mesh files.


Hope this helps.

[AlbertoArtoni]

Thanks for the answer.


It turns out that polyDualMesh uses polygons centres instead of centroids: if the original mesh is a Delauny triangulation it should generate planar faces.



We obtained some reasonable results, although new problems arose and then we lost interest in the whole procedure since the mesh generation was not the main focus.