use local, make a surface of revolution around the local region and assign the rotational properties tot he region - not the part rotating. If room exists put hte volume of revolution between rotor and stator. See example problem.
Thanks for the guidance. I am trying what you said to do. I read the advanced tutorial for rotating impeller but there are some doubts. Do i need to encapsulate each rotor with surfaces. I mean should I make a hollow volume with offset surfaces to encapsulate the whole rotor part and then mate both, i.e part's outer faces and created volume surface's inner face while assembling pump (in sample fig-2 that grey one is hollow casing type thing for inner rotor) ?? Next doing that to both rotors will cause a increase in tip clearance which will reduce the efficiency. For now I have resolved it by keeping the tip clearances still constant & calculating and adjusting the offset volumes so that now they will contact each other in assembly while rotors will still maintain the clearances. I am just telling you the steps that i have understood but yet I havent implemented it. Please tell where I am getting it wrong...!!
1. I should make a part enclosing to original rotor and save it as differnet part. In fig-2 i have called a rotor and hollow volume(both are differnt part) for it that I made.
2. Under assembly i shud mate each surface to respective rotor and fix it with them.
3. I shud disable this newly created surfaces/volume(for both rotors) in flow simulation and shud apply local rotation to these surfaces/volume and not to parts.
4. there is a fluid volume trapped between rotors and also in ports just under them. Shud i make a thin film surface there also(like end float clearance) and will disable it while simulating (to let the software understand gap between fluid volume trapped & moving between rotors and that flowing in ports which currently it is treating joined...i guess)
Thanx a lot again for bearing with me !!