I am simulating a mixture of gases flowing through a nozzle and exiting into the atmosphere to see temperatures/velocities/concentrations at the nozzle exit.
Usually Flows are expressed with balance equations. It could be used in a Euler's transport equation, such as the continuity equation. First, the equation must be set up and then implemented in Comsol as PDE.
Thanks to everyone! Eventually I used Comsol CFD and heat transfer module (it has the built-in equations) and for gas mixture I used the concentrated species transport module with Stefan- Maxwell diffusivities.