Rotating region of a centr. pump - Counter R wall

Emre

Hi, I am simulating a centrifugal pump. I had drawn the region within the housing in UG. Then, I seperated the part into two parts first of which is the region of blades, and second one is the gaps around the impeller(radial and axial). Now the gap part is like a coating around the impeller. My question is that: 1) Am I right with seperating the inner region of the housing like this? 2) I adjusted both the impeller and gap region it as rotating and used counter r wall at the outer surface in the gap region. Or should I adjust the gap region as stationary and use a frozen rotor interface? 3) I also have a region around the lower part of the impeller. Should I adjust the wall near the impeller as rotating as the same speed of impeller? Could u help about these topics because I am on the edge of my research on these. There are no more articels or books or tutorials.