Symmetry boundary with 180 deg rotation?

sharpep@uoguelph.ca · January 10, 2025, 17:09

Hello,
I'm relatively new to CFD/OpenFOAM.
I have a large domain, multiple fan inlet/outlet problem.
I would like to halve my domain using some sort of rotational symmetry boundary, but don't know quite how to accomplish this.
A sketch of my domain (top view) is attached. The right side (greyed out) is the same as the left side, rotated 180 degrees about the red dot in the middle.
Any advice would be greatly appreciated.
Thanks,
Peter

tomf · January 11, 2025, 06:56

Hi Peter,

If I understand you correctly you would like to have a rotational symmetric solution around the center axis of your domain in top view?

My first suggestion would be to look into cyclic or cyclicAMI boundary conditions if you are using any of the recent OpenFOAM versions from ESI. If you are using a version from the OpenFOAM Foundation, it depends on what version there is to use exactly. cyclic could still work, otherwise it is either cyclicAMI or NCC, but I am not so sure if that development would allow your case.

The other advice I have would be to make a very simplified version first to test the idea. So not using fans, just an inlet in the lower left part and an outlet in the upper left part with a separating wall in between?

It does sound like it could be difficult to get the flow pattern you would expect, but this is the direction I would investigate first.

Good luck,
Tom

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January 11, 2025, 06:56		#2
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 654 Rep Power: 33	Hi Peter, If I understand you correctly you would like to have a rotational symmetric solution around the center axis of your domain in top view? My first suggestion would be to look into cyclic or cyclicAMI boundary conditions if you are using any of the recent OpenFOAM versions from ESI. If you are using a version from the OpenFOAM Foundation, it depends on what version there is to use exactly. cyclic could still work, otherwise it is either cyclicAMI or NCC, but I am not so sure if that development would allow your case. The other advice I have would be to make a very simplified version first to test the idea. So not using fans, just an inlet in the lower left part and an outlet in the upper left part with a separating wall in between? It does sound like it could be difficult to get the flow pattern you would expect, but this is the direction I would investigate first. Good luck, Tom