Retraction dynamics of an impacting droplet on a rotating surface

A water droplet impacting the center of a rotating superhydrophobic surface is experimentally observed with high-speed side-view imaging to examine the bouncing and retraction dynamics. The circumferential velocity in the retracting liquid film generates a centrifugal force which either induces rapid rebound like a spinning-top or leads to drop break up. A model is used to predict the retraction and circumferential velocities. We find that the droplet rebound is weakened by the centrifugal force with a transition between the two regimes around a critical Froude number (Fr=2.4). Good agreement is found between the theoretically predicted parameters and the experimentally measured ones.