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-   -   boundary condition for derivative of velocity (http://www.cfd-online.com/Forums/cfx/24366-boundary-condition-derivative-velocity.html)

Daiga August 6, 2007 05:56

boundary condition for derivative of velocity
 
Hello everybody,

Is it possible to set dv/dn=0 (derivative of the velocity in the direction of surface normal). I need a boundary condition for the boyant flow in inclusion where I can calculate one half of boyancy vortex (to take into acount only one half of each fluid inclusion - there is only one vortice in each inclusion).

In my case there are many fluid inclusions in the solid structure where boyancy takes place. It would be necessary to use the symmetry of temperature field (it cuts fluid regions symmetrically) to get reasonable mesh size. The problem of setting boundary conditions on cutted fluid region remains.

Looking forward to hearing any useful suggestion.


Aghakhani December 7, 2009 08:47

velocity derivative
 
I have this problem too, please help me to find a way for impose velocity derivative boundary condition.

ghorrocks December 7, 2009 18:11

This boundary condition is not included in CFX. If you want to do it you will need to do it in user fortran.

Also consider moving the boundary further away and using the existing simpler BCs. That may be easier and more accurate.


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