varied pressure boundary condition...help???

PA

I am working on an airbox simulation where air enters with certain velocity and exits through an outlet. There is a certain static pressure being exerted at the outlet. I know the inlet velocity and the static pressure at the outlet at the initial conditions. Later the variation of the pressure accorss the outlet is dependent on the velocity component just before the outlet given by an expression.

My question is can i set the pressure at the outlet to vary with respect to the velocity of the air just before the outlet? If yes How can i do it?

Any help is greatly appreciated.