Yes, I would avoid the outlet boundary condition. I wish they would deprecate this boundary condition or at least restrict it to the TUI.
Mathematically, for incompressible flow, one boundary condition (BC) should be a pressure and another a velocity or mass flow rate. Think back to your partial differential equations class. Remember the hyperbolic, parabolic and elliptic equations topic? This is why we had to learn that. When we move to compressible flow the momentum equations transition to hyperbolic and the characteristics of the equations let us specific two upstream BCs and that is why you see the option for supersonic pressure.
Reading back through your case, you could go with a pressure inlet and a mass flow outlet, this would be the equivalent to the velocity inlet and the pressure outlet. The key is to have a control point on both the mass and momentum equations. Depending on what is just upstream of your simulation domain, it may be valuable to have a non-uniform inlet velocity (for example: fully-developed parabolic). This would help reduce an artificial pressure drop created near the inlet.
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