External Flow Boundary Conditions
 

Hello everyone,

I was wondering why for standard 2D external flow boundaries (top, bottom, left (where freestream originates from), and back) fixed pressure and zero-gradient velocities are used for the back, top, and bottom, while fixed velocity and zero-gradient pressures are used for the front face. Aren't these conditions imposed to reflect the return to ambient conditions as you travel from the test object? Shouldn't all sides have (the same) fixed pressure? Thanks.