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-   -   Surface normal velocity BC with zero gradient tangential, cylinder (http://www.cfd-online.com/Forums/openfoam-solving/118329-surface-normal-velocity-bc-zero-gradient-tangential-cylinder.html)

c_dowd May 25, 2013 07:22

Surface normal velocity BC with zero gradient tangential, cylinder
 
Hi all.
I have a cylindrical flow in which I am specifying the velocity at the cylinder surface (flowing inwards) and having the top of the cylinder as a fixed pressure outlet. I would like
to create a boundary condition where only the surface normal velocity (ie; radial component) is specified, and there is a zero gradient condition in the tangential directions.

Currently I'm using the cylindricalvelocityinlet condition from the following thread:
http://www.cfd-online.com/Forums/ope...-openfoam.html
which works perfectly except for the shear it applies to the flow as it moves tangentially against the boundary. Basically I want a flow where no vorticity is generated (except along the bottom boundary), which is not what I am currently getting. Below I've attached a plot of the vorticity in the out of page direction, showing the effect of the shear on the flow.

http://i.imgur.com/5QnnoOT.png

I don't have a good enough understanding of the BC codes to create my own, and I'm not sure how I would create such a condition in groovyBC. Any help?


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