But then I select this:
Hi @vtsich,
The error is due to the fact that you’re assigning a no-slip boundary condition to the volume (blue cylinder) which defines the rotating zone. That is not a solid part properly but only the definition of a cell zone within the domain.
You need to apply the no-slip boundary condition only to the walls in grey which belong to your pump.
Best,
Igor
It will work or it will be wrong. I have thought about it but I don’t know what the rest of the zone will do?
Thank you very much for your help! 
You’re welcome!
The rest of the zone will define your domain in that region as rotating, except from the parts you explicitly define as stationary.
Ok .Simple will rotate without the flow right ?As long as it protrudes from the static wall
Good evening. If you can see this condition again if it is correct before I do an experiment because I have limited computers. Static wall means no slip wall right?
Hi @vtsich I’ve just run an experiment and the wall ceased to move as expected. I’ve just set the “Static Walls” as no-slip walls, but I had to manually deselect the ones you’ve added to the rotating wall boundary condition:
Here is the project I was working on: SimScale Login
Best,
Igor
Can you set it somehow in Edit CAD or is it not possible?
I did this. Will it work?
Since I have limited computing resources, can you test if the corrected project works?