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-   -   Velocity profile boundary condition (http://www.cfd-online.com/Forums/flow-3d/116357-velocity-profile-boundary-condition.html)

Tuca April 17, 2013 14:40

Velocity profile boundary condition
 
I was trying to simulate air flow around a building and I would like to set a velocity profile as the inlet boundary condition in the domain.

The standard velocity boundary condition on FLOW-3D sets up an uniform velocity profile, but I was trying to avoid considering a buffer region to let the velocity profile to develop.

I have tried a combination of outflow and grid overlay boundary condition following the application reported in http://www.flow3d.com/resources/news...stockpile.html. However, applying a pressure boundary condition at zmax completely deformed the velocity vectors (they were pointing downwards). I solved it by applying a free-slip wall boundary at the top (the results were the same using a symmetry boundary condition also) but I lost the reference pressure by doing so.

After several attempts I managed to get some results that resemble experimental results published in the literature for a simple case of the air flow around a forward facing step by using a restart option in order to use the velocity profile set up as initial conditions as a boundary condition using the grid overlay option.

My doubt is that my approach looks very awkward and not intuitive and I was wondering if anyone as came across the same problem (setting up a velocity profile as boundary condition in Flow-3D) and has a more elegant solution

JBurnham April 23, 2013 13:02

The most elegant solution would be to customize the bc.f routine to set a specified velocity/TKE/DTKE profile at the boundary. See the User Manual chapter on customization for details of how to approach editing and recompiling routines.


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