Negative cells volume while reading Fluent .cas file

Development
1

I would like to load a Fluent .cas file using Fluent case reader in paraview. After loading the file, it appears that the mesh contains elements with negative volume (I checked this with the Cell Size filter). Let me just add that “Check mesh” in Fluent returns all positive volumes and no problems with the mesh.

The elements with negative volume belong to the boundary layer. In the image below, I have overlapped the original mesh and the Cell Size filter after the treshold operation (I am displaying only cells with negative volume). You can see that the problem is with prismatic cells.

Has anyone experienced similar behavior before? Maybe there is a simple way to remedy it?

image
image1920×793 218 KB

2

Please share your data.

3

I prepared a smaller case on which the same thing happens.
test_geometry.cas (2.5 MB)

Localization of cells with negative volume:

image
image1777×886 270 KB

Treshold and isolate cells with negative volume:

image
image1777×886 29.7 KB

I hope its enough

4

please share the .dat file too.

5

Consistency of the volume of the Wedge element seems to involve complications, but the most immediate fix would be to modify the following two lines in the PopulateWedgeCell() function in vtkFLUENTReader.cxx.

  if (this->Faces->value[base].c0 == i)
 → if (this->Faces->value[base].c1 == i)

and

  if (this->Faces->value[top].c1 == i)
 → if (this->Faces->value[top].c0 == i)

Note: The same modifications will be needed for vtkFLUENTCFFReader, which follows the vtkFLUENTReader implementation.

6

Thanks for the answers

I’ll try to do the same from the code level with the modifications Kyoshimi suggested and let you know if I succeeded