I am new in flow simulations. For a University project I have to simulate a constant flow mask. A blower supplies the open mask body with air. We have to determine the flow rate and pressure so that (independent of the breathing pattern) no outside air can enter the mask through the exhalation ports. Valves should not be used and furthermore carbon rebreathing should e avoided.
For the rebreathing of CO2 I would look at the mass fraction and try to avoid accumulations of exhaled air. But I have no idea how to simulate the mass flow of ambient air entering the mask body. Do you have any ideas?