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-   -   parallel mode - small problem? (http://www.cfd-online.com/Forums/fluent/33764-parallel-mode-small-problem.html)

co2 May 19, 2004 12:32

parallel mode - small problem?
 
hi folks,

When I try to solve my natural convection problem (2d. axisymmetric) on a single processor, serial mode 2GB machine, it is taking too much time. My time step size is 0.2 sec, My experiments are 30 day long .. so it is just imposssible to wait to get all the results from a single processor.... So I was thinking running fluent in parallel. We do have several available processors here and those certainly can be used. I have been reading about parallel processing related questions on this forum for the last few hours. I noticed that if I try to solve a small problem in fluent parallel, then actually I can end up spending more time in parallel as fluent spends too much time in communication. We do have a 100 MB/sec connection speed University LAN which is very good. My problem has only 30,000 cells. Should I really attempt to solve this problem in parallel .. I just can not imagine running this model for over 30 to 40 days of actual time and then comparing results .. please suggest some solution. Time step size can not be increased as i am dealing with buoyancy driven flow and I want to preserve accuracy ..

Chetan Kadakia May 20, 2004 02:40

Re: parallel mode - small problem?
 
I don't think you need this in parallel. You may need a small time step to stabilize the solution initially, but you can then gradually increase the time step. what unsteady phenomena are you looking into?

Arun June 1, 2004 23:47

Re: parallel mode - small problem?
 
Hi co2!

You could try to run your case in parallel. But since you have only 30,000 cells make sure that you use optimum number of processors so you dont waste time in communication between blocks. You could refer to the Fluent site as to what would be the optimum performance you can expect for your class of problems, provided they have one. All the best.

Arun


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