[blyatman]

I have a simple setup with 2 boundary surfaces: one is a velocity inlet, and the other is outflow. The flow is single phase and incompressible, with no energy equation.

My question is: if pressure is not specified anywhere in the domain, then how is pressure calculated? I understand that since the flow is incompressible, only the change in pressure is relevant, but doesn't Fluent still need to fix pressure at some location to solve for the pressure field?

A similar follow up question would be if you specify one surface as a pressure inlet and the other as a pressure outlet, then how is the velocity field calculated since the velocity (and hence mass flow) is not specified anywhere?