[Sugajen]

Hi Tobi,

I am new to OpenFOAM. I have a similar case where I am getting a lot of faces with face pyramid volume < 1e-13 that is causing my IcoFoam solver to crash. The Co number becomes too high right from the second time step.

The mesh was done using snappyHexMesh and checkMesh says the mesh is OK. I tried a lot of changes that are suggested in the forum to no avail. Could you please have a look at the case file?

https://www.dropbox.com/s/lmloepj5i1...se.tar.gz?dl=0

Thanks,
Sugajen

Originally Posted by Tobi

Hey Bruno & Zannatul,

I checked your case and I am wondering why you use edge refinement instead of surface refinement in that case? There is no need for edge refinement. Use surface refinement and you will be a happy man.

If I run your case without modifications, one of the first big problems that occur direct after castellatedMesh is:

Checking initial mesh ...
Checking faces in error :
    non-orthogonality > 65  degrees                        : 0
    faces with face pyramid volume < 1e-13                 : 542552
    faces with face-decomposition tet quality < 1e-09      : 0
    faces with concavity > 80  degrees                     : 0
    faces with skewness > 4   (internal) or 20  (boundary) : 0
    faces with interpolation weights (0..1)  < 0.02        : 0
    faces with volume ratio of neighbour cells < 0.01      : 0
    faces with face twist < 0.02                           : 0
    faces on cells with determinant < 0.001                : 0
Detected 542552 illegal faces (concave, zero area or negative cell pyramid volume)

[Moderator note: Moved from extrudeMesh + snappyHexMesh 2d wedge mesh]

[Sugajen]

Hi everyone,
It would be great if I can get your opinions on this. I've been stuck here for a week now.
Thanks in advance!

Sent from my ONE A2005 using CFD Online Forum mobile app

[Sugajen]

Hi all,

I am new to OpenFOAM. I created a mesh using snappyHexMesh where I am getting a lot of faces with face pyramid volume < 1e-13 that is causing IcoFoam solver to crash. The Co number becomes too high right from the second time step.

The mesh was done using snappyHexMesh and checkMesh says the mesh is OK. I tried a lot of changes that are suggested in the forum to no avail. I am attaching the case file below. Please do have a look and any suggestions or directions are most welcome.

Thanks in advance!

https://www.dropbox.com/s/lmloepj5i1...se.tar.gz?dl=0

Checking initial mesh ...
Checking faces in error :
    non-orthogonality > 65  degrees                        : 0
    faces with face pyramid volume < 1e-13                 : 542552
    faces with face-decomposition tet quality < 1e-09      : 0
    faces with concavity > 80  degrees                     : 0
    faces with skewness > 4   (internal) or 20  (boundary) : 0
    faces with interpolation weights (0..1)  < 0.02        : 0
    faces with volume ratio of neighbour cells < 0.01      : 0
    faces with face twist < 0.02                           : 0
    faces on cells with determinant < 0.001                : 0
Detected 542552 illegal faces (concave, zero area or negative cell pyramid volume)

Thanks,
Sugajen

[Sugajen]

Hi all,

I solved it using setting the minVol to 0 in snappyHexMeshDict. I am not sure if that is the right way but it solved the issue as of now.

Best,
Sugajen

[SimonStar]

Hello,


Yes it is a way to solve it but what I know is that there is a reason for the minimun cell volume.

It can make your simulation more instable for example if the solver has to divide through a cell volume that is allmost zero.

But the question is still there:
What happens if I got such cells in my mesh?


Thank you
Simon