VOF for water drop in air
 

Hallo all, I'm trying to simulate a free fall of a single water drop in air. The drop diameter is 200 micron. The calculation field is 0.2x2 cm. I use the unsteady VOF geo- reconstruct model in Fluent 6.2. Time step is 5e-5. My problem is that after a few time steps I get an un-physical deformation of the drop (though the flow field is converged!)