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-   -   Problem with cyclic patches (http://www.cfd-online.com/Forums/openfoam-solving/95081-problem-cyclic-patches.html)

sven December 5, 2011 15:27

Problem with cyclic patches
 
Dear Foamers,
I tried simulating a nozzle guide vane flow with cyclic patches. Unfortunately I cannot get my case working in OpenFOAM since several weeks. I already tried a lot of things but I cannot get the thing to work.
The problem seems to be caused by the cyclic boundaries of my flow domain. I am simulating one channel between a pressure side of a vane and the suction side of the adjacent vane. The vanes are walls and before and after the vanes I have an inlet and an outlet section like in a turbine. These sections are both periodical (cyclic) in the direction perpendicular to the flow. Normally the flow should be parallel to these inlet and outlet sections. However, what happens in OpenFOAm is, that only for a short distance at the inlet section the flow is parallel to the inlet section and then makes a quite strong turning (about 90 degrees) and almost the whole mass flux goes out through the cyclic patch, causing divergence of the solver.
I made the cyclic patches with the createPatchDict, that was downloadable here from the CFD forum and other people reported that it worked. However, I could not get it to work in my case. I checked the boundary conditions and everything over and over, running always into the same problem. Even with different solvers the same problem occurs. When setting the cyclic patches to walls, everything works fine and the flow is as it should be. Do you have any good suggestion or any idea what the problem might be? Is there any other way to create cyclic boundaries in OpenFOAM or does anyone know how to solve this problem. Thanks a lot.


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