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-   -   Visualization problem on ParaFoam (http://www.cfd-online.com/Forums/openfoam-paraview/104848-visualization-problem-parafoam.html)

Rider July 17, 2012 06:25

Visualization problem on ParaFoam
 
Hi FOAMers,
I have different problems with the use of paraFoam. At the beginning I thought that the problem was in my snappyHexMeshDict file, but some people told me that the problem was a bug of paraFoam. I try to solve this problem with the polyHedral option, but paraFoam crash when the number of cells is too important.

The picture 1 is without polyHedral option and the picture 2 is with this option..

http://img15.hostingpics.net/thumbs/...07picture1.jpg


http://img15.hostingpics.net/pics/720244picture2.jpg

Currently, I try to use the foamToVTK converter. I use this command ligne :
"foamToVTK -latestTime" and I have the picture 3. I research the results of the picture 4 (without parts of cut cells), can you explain me how to obtain it ?

http://img15.hostingpics.net/pics/452663picture3.jpg

http://img15.hostingpics.net/pics/279942picture4.jpg

Thanks for your help,
Rider.

wyldckat July 17, 2012 16:00

Greetings Rider,

Have you tried the option "-poly" with foamToVTK?

Additionally, for inspecting a section cut of a mesh, use the "Extract Cells" feature instead, which will not trim your cells... although it's a bit buggy with polyhedral meshes.

Furthermore, try this instead as well:
Code:

paraFoam -builtin
This will open the case with the internal reader.
At the bottom of the "Object Inspector", you'll find the option for the polyhedral mesh as well.

Best regards,
Bruno

Rider July 18, 2012 03:37

Greetings Bruno,

Thank you for your answer. I tried your propositions but it don't works (or it's me ...)

If I upload my files, can you try ?

Best regards,
Rider

wyldckat July 18, 2012 16:08

Hi Rider,

I suppose I can try figuring out what the problem is if you upload the case, as well as indicating where I should look at ;).
If the data of the case is sensitive, send me the link via private message.

By the way, was does checkMesh tell you about the mesh? Very skew faces is a good reason for even ParaView to have problems representing the mesh!

Best regards,
Bruno

Rider July 19, 2012 05:51

Greetings Bruno,

I sent you a private message.

If we can find a solution I'll post it here for everybody.

Best regards,
Rider

wyldckat July 20, 2012 10:02

2 Attachment(s)
Hi Rider,

Yep, using polyhedral mesh with section cut crashes ParaView with this error message:
Code:

Qt has caught an exception thrown from an event handler. Throwing
exceptions from an event handler is not supported in Qt. You must
reimplement QApplication::notify() and catch all exceptions there.

terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
Aborted

But as shown in the attachment, you should use the filter "Extract Cells By Region"! This way you do in fact examine properly the mesh ;)


By the way, I also tested using the internal reader by running:
Code:

paraFoam -builtin
Notice the option on the lower left of the "Object Inspector", where I unchecked the option "Decompose polyhedra"!

Best regards,
Bruno

Rider July 23, 2012 02:53

Thank you very much Bruno!

This is the result that I was looking for :)

Best regards,
Rider.

sdharmar January 8, 2013 16:00

2 Attachment(s)
Hi Bruno and Foamers,

I have a problem in visualization my mesh in paraview with openFoam. I have attached two snap shots of the same case with different cell numbers.

When I use 3.1 millon cell case paraview fails to show me the geometry (openFoam1.jpg). The other one shows with around 400000 cell case which doesn't have any probelm. I ran two cases with the same conditions. But couldn't see results for the 3.1 million case.

Please help me if you have encountered a similar type of thing.

Best,

Suranga.

wyldckat January 8, 2013 16:23

Greetings Suranga,

Looks can be deceiving ;) Even if it looks like it didn't load, there was no error message! What happened is that ParaView will display by default a heavier mesh in "Outline" mode, to avoid locking the user out. If your mesh had 1000 million surface cells - and assuming you had enough RAM - it could take a few good 5-10 minutes just to load the surface mesh.

If you compare the two snapshots, you'll see that in one it says "Surface" and in the other "Outline".

Don't see where it is yet? OK, see the Help menu? Then on the second line of tool-bar buttons below it, a bit to the right! There, one says "Surface" and in the other "Outline". :D


My apologies if this description seems a bit patronizing, but when I saw the two snapshots you attached, in a simple comparison with back-and-forth the solution can be seen! ;)

Best regards,
Bruno

sdharmar January 8, 2013 16:53

Thank you very much for the prompt reply. I need to pay more attention in the future.

BR,

Suranga.


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