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-   -   Normal velocity at the symmetry boundary (http://www.cfd-online.com/Forums/fluent/69353-normal-velocity-symmetry-boundary.html)

Seventy October 20, 2009 12:38

Normal velocity at the symmetry boundary
 
Hi, I am new to Fluent but have some background on fluid mechanics. I notice a problem in Fluent and don't know how to explain it. I have a 3D k-e model with a symmetry boundary. The velocity normal to this boundary should be zero according to the definition of symmetry, but the converged solution shows none-zero normal velocity exists on this surface. A similar case is the OUTFLOW boundary. By definition, OUTFLOW boundary should have zero normal flux, but I observed none-zero normal velocity gradient in a contour plot on the surface. Could anyone explain the reason please?

regards,
Steve

t.krishnamohan October 26, 2009 07:52

Steve,

When a boundary is defined as symmetric, the gradients of all the properties normal to it will be zero. You are misunderstanding the properties with its gradients.


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