FIG. 3 . Partial-coalescence-rebound (PCR) regime. (a) Selected image sequence of impact and rebound behaviors of two droplets on a flat superhydrophobic surface with L =1.67 and We =35. The velocity fields are extracted along the mid y (b) and the midx (c) plane passing through the box. The normalized time is defined asτ =t /(ρR 03/)1/2.