CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM (http://www.cfd-online.com/Forums/openfoam/)
-   -   define cutting plane - parallel running (http://www.cfd-online.com/Forums/openfoam/66795-define-cutting-plane-parallel-running.html)

Schag July 24, 2009 04:50

define cutting plane - parallel running
 
Hi,

I'm looking for a solution to define a cutting plane for parallel running.
My domain is a U pipe, with an inlet lenght different from the outlet one.
Looks like that:

inlet...... xxxxxx
.................... x
.................... x
outlet xxxxxxxxx


The problem is that methods simple/metis/herarchical do not cut it at the middle of the U turn, so the interface is not optimal. I could eventually use a manual method, but don't have an example of implementation. Is there another solution?

Regards

Julien

henrik July 24, 2009 05:21

Julien,

how many processors?

It's important to have an equal amount of cells on each processor. The size of the processorProcessor patch is secondary.

Henrik

Schag July 24, 2009 07:44

Only 2 processors for the moment, about 160k cells each...and 1200 faces for interface.
I have no temporal gain compared to monocore simulation...

henrik July 24, 2009 08:03

Dear Julien,

did you start your simulation in parallel?

Code:

mpirun -np 2 julienFoam -parallel
Henrik

Schag July 24, 2009 08:42

yes, I did that correctly I think, I used that command line, and my 2 processors are busy.

I have a gain in executionTime, but not in clockTime (and the computer isn't doing anything else at the same time).

I though, maybe my computer is not adapted to that kind of parallel using. (AMD Athlon(tm) Dual Core Processor, Debian 64bit)

henrik July 24, 2009 10:26

Julien,

your hardware is fine.

Quote:

I have a gain in executionTime, but not in clockTime (and the computer isn't doing anything else at the same time).
I am confused about this. Please post the log of last few iterations.

Please check in top that the two processes together consume about the same memory than the single processor process.

Which parallel comms library are you using?

Quote:

echo $WM_MPLIB.
Try a different one. LAM rather than OPENMPI or vice versa. You probably need to compile Pstream.

Incidentely, is this a binary installation? If yes, it might be worth a try recompiling everything.

Henrik


All times are GMT -4. The time now is 13:19.