Rebound behaviors of droplets impacting on a superhydrophobic surface

The rebound behaviors of droplets impacting on a self-fabricated superhydrophobic brass surface (WCA=164.5^°) were observed and studied by using high-speed-camera. In accordance with energy conversion, theoretical analysis of different behaviors and rebound mechanism were given. At lower velocities, three behaviors in different velocity ranges were observed: partial rebounding, entire rebounding and ejecting during rebounding. At higher velocities, such two behaviors as rebound after splashing and rebound, ejecting after splashing, occurred alternately and exhibited certain periodicity. A function to predict the critical impact velocity is derived from energy conservation condition, and the prediction values tally with the experimental values, with the maximum relative error about 14%.