### Author Topic: Rotating Domain and a Stationary Domain with rotating walls in CFX?  (Read 2716 times)

#### pitney1

• Jr. Member
• Posts: 62
• Reputation: +0/-0
• Searching for solution
##### Rotating Domain and a Stationary Domain with rotating walls in CFX?
« on: May 11, 2012, 10:56:44 PM »
What is the difference between using a Rotating Domain and a Stationary Domain with rotating walls in CFX?

#### william

• Full Member
• Posts: 151
• Reputation: +14/-0
• Know it, share it.
##### Re: Rotating Domain and a Stationary Domain with rotating walls in CFX?
« Reply #1 on: May 11, 2012, 10:57:12 PM »
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.