[Ema40]

Hi.

I am simulating a open channel flow. I have imposed a mass flow inlet, a pressure outlet and lateral wall. The only boundary I can't understand is the top of the channel, which is open to the external environment.

1)Which boundary condition is more appropriate? Pressure outlet with gauge pressure =0, pressure inlet, inlet vent or outflow (since the air can go out across this boundary)

2)Since it is an open channel, there is air which enters/exits the domain through the top boundary over the flowing water, avoiding overpressure or underpressure in the domain. The boundary condition in 1) is able to provide this?

3) At the inlet I know the mass flow rate of water and I impose it. But I think that there is also air that enters, as it happens in a classical open channel. But how much air? can 1) provide to supply air and avoid under/over pressure?

thank you