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Old   January 5, 2017, 07:49
Default maximum number of faces?
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Hi there,

I already asked this questions in a different thread (Calculation of number of faces sHM), but I think it's not limited to snappyHexMesh so I post my question here as well.

What is the maximum number of faces in openfoam?

During meshing I get a negative number of faces:
After refinement gap refinement iteration 1 : cells: 888 490 165  faces: -1 563 835 164  points:952606417
shortly afterwards snappyHexMesh crashes.
My idea is, that the number of faces is stored as a 32 Bit Integer. So the negative face number has something to do with the 32 Bit Integer Limit, because die number of faces of would be higher in this example.

I tried to find something in the source code, but I'm not familiar with it yet, so it's hard for me to find anything. In the snappyHexMesh.C Source code I found where faces are gatherd (line 462)
// Gather all faces
List<faceList> gatheredFaces(Pstream::nProcs()); 

gatheredFaces[Pstream::myProcNo()] = allBoundary.localFaces();         

forAll(gatheredFaces[Pstream::myProcNo()], i)
inplaceRenumber(pointToGlobal, gatheredFaces[Pstream::myProcNo()][i]);                                    
But I didn't find the "number of faces" for the output or a maximum number of faces.

Maybe someone who's more familiar with the source code could give me a hint?

Thanks for your help!

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Old   January 5, 2017, 09:53
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okay, I figured it out myself. Just in case anybody is interested:

Starting from line 2692 in the meshRefinement.C Source Code ( the output for the number of faces is defined. The number of faces is stored in the label "nMasterFaces".

With echo $WM_LABEL_SIZE ( you can check the size of your labels, 32 or 64 Bit.
In my case its 32 Bit, so I assume this is the reason why I get a negative face number and sHM crashed.

Depending on your system (if 64Bit is possible or not) you can change the LABEL_SIZE in your bashrc file.

Just for completness, the link to my other post where I asked this question: Calculation of number of faces sHM
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