[mahdimazloom]

Hi everyone

I am trying to solve two degree-of-freedom VIV of a flexibly mounted cylinder
in tow dimensional cross flow using COMSOL 4.4 FSI module (No turbulence model, DNS).

I have defined a spring foundation at the center of the cylinder in 2 directions
the simulation runs successfully at some flow velocities but at some other
as simulation continues the cylinder mesh starts to rotate and therefore deforming the fluid mesh resulting in absurd vortex shapes and finally errors.

Can anyone help me with that. Is there any way I can prevent cylinder mesh from rotating ?