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MRFsimpleFoam + Porosities in parallel

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Old   September 9, 2009, 09:15
Default MRFsimpleFoam + Porosities in parallel
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BastiL
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Dear all,

I have massive trouble with the parallel scaling of MRFsimpleFoam on our cluster. The solver has been slightly modified (added porosities) and is from the 1.5-dev. It contains some ggis - this might be important for parallel performance. I compare with FLUENT runs from 1 to 32 cores on a myrinet cluster and so far I have (still running):

FLUENT:
2Core: 13,739s
4Cores: 5,594s
8Cores: 3,458s
16Cores: 1,609s
24Cores: 1,215s
32Cores: 950s
This looks quite reasonable for me. Same model on OpenFOAM:
8Cores: 12,752s
16Cores: 14,647s
32Cores: 20,444s
Very strange - slowdown instead of speedup and in general very slow.
Are there some specialities for ggi, MRF and porosities in parallel? What might be wrong? May it be worth trying a benchmark case? which? Any ideas?

Regards BastiL

Last edited by bastil; September 9, 2009 at 09:39.
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Old   September 9, 2009, 10:39
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Ok after investigating little further this improves rapidly as soon as tuning of ggis (even keeping same decomposition). GGI-performence in parallel still seems to be an issue for large cases running on more than 8 cores.

Regards BastiL
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