Problems after snappyHexMesh with paraview
 

Hi

I have a problem with my simulation case and I am still unexperienced enough to solve the problem. Hope you can help...

In my case I have a geometry which exist of different 5 stl files.
I have tested all my setting with a very coarse background mesh and only one single stl file (out of these 5).
Everything went (from my point of view) ok and the geometry looks quite ok after using snappyHexMesh.

Now I have excess to a supercomputer facility and prepared the case with a much finer mesh and all geometries. For the simulations I've used 80 processors for a parallel application (depomposePar). After the snappyHexMesh step I've looked into the log file of the meshing process the meshing report says that the mesh is ok.

And here is my problem.
If I try to open the meshed geometry in paraview (by using paraFoam in the case directory), paraview shows only the block mesh with the different patch names. I also tried to reconstruct the case (with reconstructParMesh), but with the same result.

What is wrong here. Any help is very much appreciated!

Thanks in advance
Andreas

Just one quick thought, did you chose the option (dropdown) to view the decomposed case in paraview?

That was one of the problems. There was no option bottom (decompose/reconstruct).

I am not at my computer but you might need to launch paraFoam -builtin to get that option.

Hi Matthew

thank you for the hint, but I have still the same problem.
I have attached the log file of this job (I needed to shrink it a bit...). It looks to me that everything is ok and I would expect that I am able to see the meshed parts in paraview. But I don't. I am a bit helpless. Does that mean that the meshing process failed or that there is only a visualisation problem?

File/case information:
In the log file there are all information from the blockMesh, decomposePar and snappyHexMesh step. I deletetd most of the snappy-output because of the file size limitation here. But there were not error/warnings or something.

After this process it worked not on paraview. Then I tried to run: reconstructParMesh, but with the same problem.

Thanks.

Andreas

Hi,

Take a look at your log:

as you ran snappyHexMesh without -overwrite flag it saved mesh from every iteration into different time folder. I.e. 0 is your blockMesh, 1 after first snappyHexMesh iteration, etc.

Thanks.

This was really helpful. I understood what happened but still. The meshed stl file is not visible.

What I did now:
1. blockMesh
2. decomposed with "hierarchical"
3. snappyHexMesh -overwrite
4. reconstructParMesh

If I look into the logfile I cannot see any error warnings, problems, etc.

I am now completely hopeless.

If the sequence of commands you've posted is exact, then

1. You create mesh with blockMesh (let's call it (1))
2. Decompose mesh (1)
3. Run 'snappyHexMesh -overwrite', so it runs in serial regime and creates mesh in constant folder (let's call it (2)).
4. Run reconstructParMesh, so the mesh (1) is reconstructed over newly created (2).

Or step 3 was definitely run in parallel regime?

Yes this is correct.
Is it a problem that I use first blockMesh and then decomposePar and the rest?


Or is it important to decompose first and then doing blockMesh, snappyHexMesh?

And yes I am sure that I have run this case in parallel!;)

Everything became rather complicated ;)

1. You say that you run commands exactly as it was written 'snappyHexMesh -overwrite'. This command runs snappyHexMesh in serial mode, to run it in parallel you should do 'snappyHexMesh -overwrite -parallel'

2. You're definitely sure about running the case in parallel.

In the log you have attached to the previous message it was clear that snappyHexMesh was run in parallel regime. But I don't see the log this time, it's difficult to say what has been happened.

Problem solved
 

Hi alexeym

thank you again for kicking my a..

I finally solved the problem with you help. I used either -overwrite or -parallel but not -overwrite -parallel.
I used the following commands:
blockMesh > log.block
surfaceFeatureExtract
topoSet
decomposePar -force
mpiexec_mpt snappyHexMesh -overwrite -parallel

Thanks again.

Andreas