how to simulate two source gas flow system?

I am working with a system that has two source gases into a single short pipe system.

One source gas is applied to one end of the pipe with constant pressure.

The other end of the pipe is open to atmospheric pressure.

The second source gas is applied in temporarily from a different port perpendicular to the main pipe.

Need to run a transient flow simulation

Any examples that you can suggest?

Thank you in advance

Fausto Bartra

SolidworksSimulation