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Proper BCs for 3D exterior plate flow with simpleFoam?

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Old   August 13, 2014, 19:06
Question Proper BCs for 3D exterior plate flow with simpleFoam?
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Ben
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If I want to run a simulation with a atmBoundaryLayerInletVelocity for the inlet and a flat plate with an object on it at the bottom but I'm not concerned with flow at the side walls or upper wall, what should be the boundary conditions for those sides and top?

Previously I've had symmetryPlane conditions on all three but when I try to reduce the width of the domain I start to see effects from the object being mirrored out side the domain. I'm up to 4.1e6 cells and I would really like to be able to cut this down for the sake of computation time. How can I have boundaries that do not effect the flow and still satisfy continuity and momentum?

Does anyone know of a similar case in the tutorials?

This would be a simpleFoam case with kOmegaSST.

Here is a link to the case files via Dropbox if that helps.
https://www.dropbox.com/sh/7u9v89yqy...3Lud2mAnzi4IUa

And a picture of the mesh as it is now attached.
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File Type: jpg cylinderAndPlateMesh.jpg (89.7 KB, 6 views)
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Old   August 13, 2014, 21:00
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Gregoire Junqua
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Hi
there is a similar case in openfoam in simplefoam turbinsiting if my memory is good
if your sides are far enough from the object you can try the slip condition. If your upper boundary is near the object i suggest to use the slip condition if near the object or if the wall is far around 20 or 40 times the height object you can set fixed value to U k and omega

hope this would help
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Old   August 13, 2014, 21:10
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Thanks for your reply,

I have examined this case but "far enough" is exactly the problem. I want to move the walls closer to the object without having flow acceleration from the constriction.
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