Two Species Boundary Condition

Iain

Hi

I am trying to model washout of a complex geometry using air. To visualize which areas are being washed out the volume is initialized through out with argon. the geometry has one opening for which the air needs to enter and the argon needs to leave, the boundary driving the flow is a deforming wall.

My problem is finding a boundary for the opening that will allow flow in both directions at a constant pressure while having a constant flux of argon.

Cheers Iain