Directional droplet bouncing on a moving superhydrophobic surface.

Droplets directionally bouncing off moving superhydrophobic solid surfaces are universal in nature and are crucial in many biological, sustainable, environmental, and engineering applications. However, their underlying physics and regulation strategies remain relatively unknown. This paper demonstrates that the maximum directional acceleration of a post-impact droplet mainly occurs in the spreading stage and that the orientational velocity of the droplet mainly originates in the early impingement process.