FSI - High convergence problem

Hi all,

I'm new to COMSOL and I have a problem that involves an interaction between air and a solid body. I am interested in the torque generated on the body by the moving fluid. My intent is to use the interpolation of the torque data obtained for different angular positions of the body, in another model to see how that solid body rotates under that torque conditions. Briefly, I have a rotor in a fluid and I divided my problem into 2 parts.

While trying to obtain the torque applied on the body for its certain angular position, I'm having difficulty in solution, probably due to solver setup. But it can be because of my FSI model if I forgot to add something necessary. Solution takes very long time beacuse of large convergence. If I increase the relative error the convergence decreases but I have to increase the relative error so much for a reasonable computing time. What else I can do? Any suggestion, advice would be appreciated.

A very simple model is attached to illustrate what I'm trying to do.

Thanks in advance,

Utku