Decomposed multiregion cases in Paraview with native reader
 

Hello all,

I'm facing a problem to post-process decomposed multiregion cases (chtMultiRegionSimpleFoam) with Paraview.
I use OpenFOAm-v1806 on a remote machine, so I cannot use paraFoam but only Paraview's native reader for OpenFOAM.

When I load my case, I select Case Type: "Decomposed Case", the reader loads the internal meshes of all the regions it finds and it works just fine.
But if I uncheck some regions (for instance to work only with one region), the internalMesh fails to load : I only get parts of the mesh like if it failed to load some processors subdomains. (I use Scotch decomposition with the same number of subdomains in every region)
I get this error from Paraview:

I tried it with Paraview 5.5.2, 5.0.1 and 4.1.0 and I get the same behavior in the 3 versions.


I've uploaded screenshots of the multiRegionHeaterRadiation tutorial to illustrate the issue. First image is from the reconstructed case and shows the topAir region as it's supposed to be. The second image is what I get when I load the topAir region as a decomposed case.

It thought I could load the whole case in paraView and then use the "extract block" filter in paraView to extract only the region I want to work with but it doesn't work. I get what is on the 3rd image. It looks like paraview mixes up regions from the different processors subdomains.

Any idea where does the problem come from or how to load regions individually in ParaView?
Is it a bug in the reader or something wrong with the case?

PS: I have to work with large cases so reconstructing the case is not an option.

Quick note: This is likely a limitation/bug in the internal reader. Please ask about this at https://discourse.paraview.org/c/paraview-support and if possible ping the forum member "olesenm" (Mark) there, because he's been doing the more recent updates to the internal reader in VTK/ParaView and should be able to look into this issue.

Thanks Bruno for the tip!

As you suggested, I posted this on the paraview support forum.
For those who are interested in this issue, here is the post : https://discourse.paraview.org/t/ope...i-region-cases

Long story short: the internal reader works perfectly fine but the issue seems to be related to the disk filesystem. The case fails to be loaded when it is written on a FAT32 or ZFS disk and I have no idea why. Or at least this is what I think to have understood from the tests I have done.

If anyone encounters the same issue or can deny/confirm this, feel free to contribute !


Yann