Xiaoxu,
Pieter's method is good idea. If you want to try something else, try this. The filter has a finite thickness in real life. You could make a thin porous domain equal to the thickness of the filter on the filter boundary of the rectangle. You don't have to specifcy the BC between the two domain, COMSOL will apply continuity directly and figure it out. For the outlet side of the filter, I would have a outflow BC.
Sri Puranam
Pieter's method is good idea. If you want to try something else, try this. The filter has a finite thickness in real life. You could make a thin porous domain equal to the thickness of the filter on the filter boundary of the rectangle. You don't have to specifcy the BC between the two domain, COMSOL will apply continuity directly and figure it out. For the outlet side of the filter, I would have a outflow BC.
Sri Puranam
