[Eman Resu]

Dear All,



I'm struggling with the problem: I would like to create a BC (pressure outlet) which will allow only one specie of the mixture to go through it.
For example, I have air and nitrogen. I would like this BC to let air go through and for nitrogen it should act like a wall.
Is it possible?

[vinerm]

In a species model, components are not treated separately in terms of convection. However, their diffusion is on component basis. In the off-the-shelf tool, as far as I know there is no provision to do what you want to. In the real world as well this would require some kind of a filter; a surface that makes one of the component deposit or convert into some other species by reaction, such as in catalytic converter.

You have to look into the objective and how this happens in the real world for your process, by deposition, active filtering, or reaction. Then you can implement it using UDF or some other approach.