[Xuekun]

Hello,

Could anyone tell me what boundary conditions should I use in the unsteady permeability problem? It is a multi-channel system with complicated bends. I want to know the final mass distribution of the gas.

How shall I define the outlet boundary condition? I don't know the final pressure, nor velocity, nor mass flux at any outlet of the modelling structure, and these are what I want to find out from the simulation.

I know there is "flow outlet" in fluent, which seems suitable for my case. But I am using Star ccm, here is what I can only choose for the outlet, which one is the most correct one?