I have a container with one inlet and one outlet. I have the area of the inlet, Ai, velocity vi of the air coming in, and mass flow mi (assume a plane with an air inlet to a bay). I don't know anything about the outlet (just that there is one). What I need to do is calculate the size of an extra hole to be made in the bay so that the pressure in the bay reaches a certain value P2, which is lower than the stagnation pressure of the air coming in the bay. I approached the problem with the Bernoulli law, as I ignore the incompressibility of the air. So I have Pstag in the bay, which is static pressure + dynamic pressure of the air coming in, and outside the bay I have the ambient pressure. Is the pressure difference between the bay inside and outside Pstaginside-Pamb or does the dynamic pressure of the air outside the pressure play a role? And after that? I can explain more if it is not clear enough. Thank you in advance for all the tips.