I have one basic doubt for rotating flows. let's say I have to doflow analysis of a turbine. I will be having one stationary domain (stator) and one rotating domain(rotor). I am using MRF Suppose my rotor is rotating at 50000 rpm. Then am I required to apply rotation to walls of blade . My doubt is whether blade walls remain stationary or not? Is it stationary wrt rotating region? So, I can do two things. (1) Apply 0 rpm in relative frame. (2) Apply 50000 rpm in absolute frame. Which one is right?

Kindly let me know the answer.

If you solve rotor region on the rotating frame, then the blade should have velocity relative to that frame. In your case, it is zero.