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Old   May 4, 2011, 14:08
Default Foam is running extremly slow
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I am working on dsmcFoam. Currently trying to simulate the tutorial case Wedge15ma5. Everything is fine when I am running the tutorial. I had tried to change the cell number in blockMeshDict. that also worked perfectly. Just took around 2 hrs to finish the simulation.

But when I tried the same case with the mesh exported from fluent (.msh file), of course the simulation is running, but it is extremely slow. It takes around 10 hrs to finish 1% of the total simulation. I have tried with different cell numbers but got disappointed.

Please help...
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Old   May 6, 2011, 14:23
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Greetings Ashok,

You are probably comparing the run times of two meshes with seriously different complexities and number of cells! Running with cells that look like bricks (the one generated with blockMesh), versus a mesh generated with Fluent, which probably is a highly hybrid mesh, you're bound to get slower run times, specially since (if I'm not mistaken) it's a particle solver.

Another thing you should check is if the mesh exported from fluent is properly sanitized; in other words, did you run checkMesh after converting the mesh to foam format? If the mesh has flaws in it then the solvers tend to be slower with it, assuming they can converge to a solution at all!

So, to sum up:
  • Run checkMesh.
  • Try a more simplified mesh, or at least less complex cell-wise.
Best regards,
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fluent mesh, openfoam, slow simulation

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