Ansys Employee

The phase diameter effects the drag, combine that with the momentum and it'll govern the droplet trajectories. Not sure why the solver would diverge with a really small step, typically if the time step is too small nothing happens. Note, as you decrease the diameter below about 10microns the relaxation time means you're near enough modelling a mist, and we often use the species model for that. 

Were you resolving VOF down to 10microns?