I am trying to simply rotate a square using the dynamic mesh feature of FLUENT. However, the mesh near the surface of the rotating square becomes scewed and negative volumes result. I have reduced the time step and am able to rotate ~50 steps (10 degrees) before the error.

The mesh is non-uniform (small near the rotating square and large near the boundary) and three dimensional. I am able to solve the problem in two dimensions with no problem.

Does anyone have any suggestions?

Use size function, and change the remeshing/smoothing parameter values, set the spring constant factor as 0.