Inlet and outlet definition problems
 

So I have been attempting to model a brake rotor with vanes for quite some time now. Initially I could not define an inlet and outlet for the rotor in the meshing, I assume because its a circular cross-section that does not appear as a plane to ansys.
Regardless, I then tried to add walls around a small section of the rotor and use the inner faces of the inner and outer radii walls to be my inlet and outlet. This appeared to work until I modeled it after calculations, where I found the the air is traveling into the metal parts of the rotor and avoiding the space I want it to flow, the channel between the inner and outer rotor face.... ugh.

My question is how can I define my inlets so it flows through the void/ channel in the rotor instead of through the solid metal... Can I do it without drawing inner and outer faces? any breakdown on how to do this would be fantastic. I am just not confident with this software yet...

Many thanks to the person who can help with this, I am going crazy.