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-   -   Wall pressure interpolation for buoyant flow (http://www.cfd-online.com/Forums/main/75513-wall-pressure-interpolation-buoyant-flow.html)

khaiching April 27, 2010 23:22

Wall pressure interpolation for buoyant flow
 
Dear CFD experts:

I am developing an unstructured code and encounter a problem whereby the flow vector is pointing in/out near the wall when buoyancy model is on.

I read from FLUENT manual that we can't set the normal pressure gradient at the wall = 0 when buoyant flow is simulated.

Can anyone please guide me on the proper method to interpolate the wall pressure? Any references to share? I need the wall pressure in order for me to evaluate the cell pressure gradient near the wall.

Please help.

Thanks a lot.

CFDtoy April 28, 2010 11:34

wall pressure
 
Mirroring is not a good method when you have grav forces. Interpolation is the best way to achieve the pressure at the boundaries. Given this, use a second order gradient interpolation to connect Pcell with Pb - gives you second order accuracy.

/CFDtoy

Quote:

Originally Posted by khaiching (Post 256584)
Dear CFD experts:

I am developing an unstructured code and encounter a problem whereby the flow vector is pointing in/out near the wall when buoyancy model is on.

I read from FLUENT manual that we can't set the normal pressure gradient at the wall = 0 when buoyant flow is simulated.

Can anyone please guide me on the proper method to interpolate the wall pressure? Any references to share? I need the wall pressure in order for me to evaluate the cell pressure gradient near the wall.

Please help.

Thanks a lot.


khaiching April 28, 2010 21:04

Dear CFD Toy:

Thanks for your prompt reply.

I tried to use the gradient projection method to interpolate the wall pressure, i.e.

p_wall = p_cell + grad(p_cell) * d; where d is vector pointing from the near-wall cell to the wall face. For the evaluation of grad(p_cell), I use Grauss divergence theorem.

Is it the method that you have suggested in your previous reply?

In fact, I still see some velocities pointing in/out near the wall.


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