create inlet and outlet fan between two fluids
 

I have a problem in simulating the air flow from a fluid domain (the upper one in the images) to another fluid domain (the other, where the garage is). In the rectangle between them, I have to put two fans, one to bring the air in the garage and one to release the exhaust air in the outside.

This might simulate the ventilation in an underground floor, trough mechanical ventilation.

For now I create a prismatic solid and gave the boundary condition "fan" for the interior; then i put velocity-inlet for the left face (1 m/s) and pressure outlet for the right face (0 pa).

Do you know how can I do that? If you need some other information, say it to me.