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-   -   Mass flow through cyclic boundary face (http://www.cfd-online.com/Forums/openfoam-post-processing/86358-mass-flow-through-cyclic-boundary-face.html)

jose_rodrig March 21, 2011 05:31

Mass flow through cyclic boundary face
 
Hi

I am simulation a section of a combustor using cyclic BC. When I was calculating mass balance and energy balance I realized that the mass flow through the cyclic boundary faces does not cancel as it should (or shouldnt??).

Can somebody shed me some light on this issue?

THX

Jose

kalle March 22, 2011 09:38

I have a faint memory of someone telling me this patch integration is not parallel (the cyclic patch crosses processor boundaries). If you have the possibility, you could try to do this on a single machine to find out if that works...

As said, a faint memory, but might be worth to check.

Regards,
Kalle

jose_rodrig March 22, 2011 12:00

Hi!

Thanks for your reply!

I solved the problem and here is how:

In the configuration I had before, I had set the cyclic patch manually in the constant/polyMesh/boundary, changing the patch type from wall to cyclic as follows (I first exported my mesh from gambit and then coupled the 2 faces with createPatch utility):

Cyclic
{
type cyclic;
nFaces 29022;
startFace 775347;
transform rotational;
rotationAxis ( 0 0 1 );
rotationCentre ( 0 -0.04 0 );
}

Then, if I eliminate the transformation entries ("transform", "rotationAxis" and "rotationCentre"), OF configures the patch automatically and now the mass balance is correct as it should be, SOLVING THE PROBLEM.

Anyway, I still dont understand what this parameters mean/do (I though I knew before :( ). I intend to look at the source for their meaning. However if somebody has a hint or answer ready to write here, it would be most appreciated.

Regards

Josť


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