I set up a moving fluid zone(rotor). The wall at the hub and the rotor itself are moving with a certain rotational speed. I defined the wall at the machine housing as a moving wall with an absolute speed that is the negative one of the moving fluid zone resulting in an stationaery wall. The simulation proceeds good. I'm wondering that in the display of the grid after a certain time the wall at the machine housing is rotated. I thought the wall at the machine housing should remain in its initial position. Does Fluent treat this wall stationaery and displays it always in the position of the adjacent fluid zone? Thank you, Thomas

(1). There are two reference frame systems, one is the stationary, and the other is the rotating reference frame. (2). If your problem can use stationary reference frame, for example the disk cavity problem, then "all you need to do "is to specify the boundary conditions in stationary reference frame. That is stationary wall is stationary, the moving wall is moving. And the fluid is in the stationary reference frame. (3).When your problem must use moving reference frame,for example the turbine passage flows, as I remember, the rotation axis must be specified for the fluid region,somewhere in GUI. Then you " must " follow the tutorial samples to set the boundary conditions. Otherwise, you will get very strange results. Your intuition is unlikely to work in the rotating reference frame ( of the code).