BC for a pressure drop simulating a drain
 

Hi everybody! This is my first post ever! I've started using openFoam for a couple of months. I'd need some help for setting boudary conditions.

I simulate drainage in a porous media. I imposed the atmospheric pressure as BC in outflow (like a drain). For velocity, I imposed pressureInletOutletVelocity boundary condition.

I was wondering if there would be a boundary condition that replicates a concentrated pressure drop at the outflow, as though the drain was less efficient. Thank you! :)