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[Salome] IdeasUnvToFoam is very slow when converting meshes

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Old   April 28, 2017, 03:31
Default IdeasUnvToFoam is very slow when converting meshes
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andrew
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I have a mesh created in Salome and saved in unv format. The mesh has 16million pyramid cells and a file size 2+gb. When I try to convert it with IdeasUnvToFoam it takes forever. That is more than an hour if it doesn't hang in the process. Smaller meshes created with the exact same procedure get converted correctly so it is not a problem in the mesh.

The procedure seems to get stuck here:

...
Constructing mesh with non-default patches of size:
left_c 91380
right_c 92058
top 98624
bottom 97796
front_c 98736
back_c 99216

Adding cell and face zones
Face Zone int 508481
....


The problem is in the IdeasUnvToFoam which seems that it can't cope to a reasonable amount of time with the conversion. I am using OF4.1 in ubuntu and salome 8.2.

Is there a way to convert or save the mesh in a diferent way to get the job done in a reasonable amount of time (a few minutes)?.

Patching the IdeasUnvToFoam is unfortunatey beyond my knowledge.

thank you in advance
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Old   May 2, 2017, 13:48
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andrew
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after some digging I found that the major problem is at the last loop which checks every face that belongs to a facezone against every face in the mesh. That in my case creates a very big amount of checks. That is for a mesh with 5.0e+5 internal faces and a 5.0e+7 total faces a total of 25e+12 checks. Even with the early breaks it is a lot of checks...

I rearranged a bit the code in the last loop to perform fewer checks but it still takes hours.


Code:
 forAll(nei, j)
                    {
                       if (c2==own[j])
                       {
                           if (c1==nei[j])
                           {
//                         Info<< "first" << endl;
                              noveau = j;
                              break;
                           }
                       }
                       if (c1==own[j])
                       {
                           if (c2==nei[j])
                           {
                               noveau = j;
                               break;
                           }
                       }
                        }
                    }
                    assert(noveau > -1);
                    indizes[i] = noveau;
                }
A better solution would be to perform a binary search in a sorted list instead of the forAll(nei, j) command but that is beyond my knowledge.

I intend to perform thousands of simulations with meshes like that so every minute counts
Does anyone have anything better to suggest?
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