Wind Tunnel boundary conditions
 

Hello Dear Foamers

I'm modelling flow inside a wind tunnel "a real experimental wind tunnel"
The wind tunnel has a devised geometry to generate a huge recirculation bubble.
the wind tunnel has two outlets, one main outlet downstream with a grid, and one bleeding outlet in the recirculation region to obtain the required pressure gradient.

I have an experimental velocity profile upstream of the recirculation region and an experimental Cp Curve at the wall close to the recirculation.

to model the grid at the outlet I tried to impose a pressure at the main outlet which corresponds to the experimentally measured pressure just before the grid.
the problem is when a pressure p is imposed at the main outlet and a 0 pressure at the bleeding outlet these pressures control the flow and force the velocity to lower values than those imposed at the inlet.
I tried to impose a constant uniform velosity at an appropriate location upwind or to use the experimental velocity profile, but the velocity just some cm from the inlet is lowerd due to high pressure in the upwind part of the channel ' pressure higher than the one obtained experimentally'

Even if i impose a 0 pressure at inlet it grows abruptly showing the same results obtained using a zeroGradient pressure.


Any ideas of how to model the grid in the main outlet without imposing a certain pressure, or any other ideas please???