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Pipe Flow with Multiple Regions for Computer Cluster

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Old   July 5, 2021, 11:37
Question Pipe Flow with Multiple Regions for Computer Cluster
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Will Crawford-Jones
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Hello,

I need to do a simulation with a large number of cells and hence want to use the university's supercomputer. As a practice run I want to simulate pipe flow with it split, cross-sectionally, into multiple (80) regions, each region being assigned to a different core on the supercomputer. I understand that I would then have to partition by region.

How do I split one region (simply a cuboid) into multiple regions? Another approach I have tried is using the 'split' feature in solidworks. When imported to Star-ccm+ these are automatically separated into 80 parts. Each of these can then easily be assigned to separate regions. The problem then is that each of these sub-regions have walls between them, which I do not want. I also tried deleting the unwanted surfaces prior to creating the regions, however, once I try to mesh this I encounter an error ("Failed meshing part 1 of 80, An edge attached to part surface "..." is free"). This is because each sub-region that is being meshed is not 'sealed', because I have deleted one of the faces. I understand that I could perhaps solve this in the "Repair Surface" feature but don't know how to do this.

I think the first approach makes the most sense, i.e., split a region into multiple regions, but how do I do this?

Thanks

Will

Last edited by wcj1n18; July 6, 2021 at 06:35.
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Old   July 6, 2021, 07:21
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Ashok Chaudhari
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Why are you splitting region into multiple? We don't need to do that for large mesh either. Software takes care of parallelization. We just need to assign a number of cores we want to use for simulation.
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Old   July 6, 2021, 08:31
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I was of the understanding that this is what partitioning was, i.e. the sub-domain that each core deals with. When I've tested across 40 cores in the computer cluster it doesn't seem any quicker than if I just use a few cores, so I was thinking that they were just sat there completely redundant. Is this understanding incorrect?
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Old   July 8, 2021, 05:17
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Let Star-CCM do the partitioning for you. It's wayyy better at it than your amateur skills

If you run on on 40 cores on your supercomputer and you don't see the speed up that you expect, then there is another issue.
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Old   July 8, 2021, 06:41
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Yes, it was a problem in my batch script and there is no need for partitioning when simulating in parallel. Thanks.
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cluster computing, multiple regions, partitioning, regions, split region


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