The rotor is full of air with water on one side of the rotor kept in place by the magnetic fluid.
The rotor is free to rotate as there?s no friction. The force on the magnetic fluid is from the centre outwards whereas the force on the rotor on the water side should be force up as it will want to float.
That's just way too vague.
Why don't you make a drawing and a more detailed description?
There was a link to a picture. It must have been taken off.