Outlet boundary conditions
 

Hi!

I'm a newbie to cfd. I'm trying to solve a backward facing step with a second order finite difference approach on a staggered grid.
I've specified the velocity inlet boundary condition (I'm using the incompressible Navier Stokes equations with artificial compressibility and they have been non-dimensionalized -> u=1.0, v=0.0 at inlet).
Which should be the outlet boundary condition? I read in different places that it should be a pressure condition. If yes which should be tha value?
Thank you!

If you are solving an incompressible case the specific value that you use is not important, because the navier stokes equations are influenced only by the gradients in pressure.