When you have rotating component in the domain it is important to understand which method should be used for modeling. Below information should be helpful for it. A Stationary Domain with rotating walls is only valid if the wall motion is entirely tangential. If there is any normal component to the wall motion, the fluid will not “feel” the pushing effect of the wall, so this is not a valid set up. For example, in rotating machines the blades have a significant normal component so they must be modeled using a Rotating Domain and stationary walls (relative to the rotating domain). In applications where the wall motion is purely tangential, then either method is valid, but one is usually preferred for numerical reasons. If the flow is mainly rotating at a magnitude similar to the rotating wall velocity then the Rotating Domain is preferred. If the axial/radial velocity in the majority of the domain is dominant, then a Stationary Domain with rotating walls should be used.