Can someone help me on setting boundary, continuum
 

Hello, can someone shed some lights on how to set the boundary conditions and continuum type? Can you pls explain each types of the boundary types i.e. wall, axis etc.? And also shed some lights on the continuum types i.e. how to use it?

I need it to simulate gas flow in a imaginary gas chamber to investigate its flow characteristic. In the chamber, should I set it wall or symmety on the surfaces on which the gas flow?

Just the above problem for now, pls help me and thank you very much!!