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Solver runs parallel on 3 cores but not on 4 or more cores

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Old   October 18, 2013, 05:55
Default Solver runs parallel on 3 cores but not on 4 or more cores
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Hrushi
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Hi all,

I am trying to solve a differential equation and I have my own solver with my own boundary conditions. Solver works fine when run serially.

Now I want to run it in parallel. There problem is, I can divide my domain on only 3 processors. When I try to run it on 4 processors or more, I run into floating point exception. But when I remove my custom boundary condition and run with a boundary condition say zeroGradient, solver works fine on any number of processors. Clearly, problem is with boundary conditions.

Question is: why using custom boundary condition is causing program to fail beyond 3 processors?

P.S. I do not have any interpolation term or any term which will cause a floating point exception in boundary condition. Yet, I encounter floating point exception.

Thanks,

Hrushi
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Old   October 21, 2013, 06:15
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Anyone? Any help?
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Old   October 21, 2013, 07:15
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it is possible that with 3 processor the boundary patch isn't divided and is completely in one "processor mesh".

With 4 processor your patch is splitted and you get the error.


i've done some programming in parallel it is possible to share some code?
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Old   October 21, 2013, 08:03
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Hi Henning,

Thank you for the reply. I tried dividing my domain in four subdomains such that the boundary in question lies only in single computational domain. However, I am still getting the same error.

No success yet. : (

I cannot share entire code but I have shared main statement of my boundary condition which I debugged to be the main culprit. Can you/ anyone figure out what is going wrong? As far as I know, there is no variable here that will cause the boundary condition to give floating point exception.

this->gradient()= -(Foam::cos(thetar_))*(scalar(1.414213562)/(scalar(2)*epsilon_))*(this->patchInternalField()*this->patchInternalField()-scalar(1));

Thanks and regards,

Hrushi
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