problems with fast rotating overset mesh
 

Currently I try to simulate a mower with to fast rotating (3000rpm) knifes. There is an overlap of the rotational movement of the knifes, so have to work with an overset mesh.

If I simulate a slower rotational Speed (<100), the calculation works fine. But when I try to calculate the high speed rotation I get a Floating point exeption, because of divergence in the turbulence variables, after 1-10 timesteps, depending on the used mesh and time step size. I've tried a wide range of cell sizes and time step sizes (1e-3 to 1e-06), but nothing works. Further I tried the most of the turbulence models that are working with overset meshes, but the result is always the same.

Are there any limitations on overset meshes that I'm not aware of?