[hellaadouni]

Hello everyone,

I'm working on a horizontal air-water confined flow, and I got the slug flow. The problem is when the slug hits the upper part of the channel and blocks the air, this air must return as I think. But it doesn't. Do you have an explanation for this?
I'm sure that the air doesn't return because the air BC is velocity inlet, but I really want to understand where did the air goes once a slug blocks its passage to the outlet?

I'll be grateful if you help me.

Thanks