Droplet Jump from Particle Bed*

Droplet rebound from a bed of mobile solid particles is central for understanding a range of phenomena including the cleaning of surfaces via the impact of water and the erosion caused by rain. We investigate droplet rebound from shallow particle beds in the unique low-gravity environment of a drop tower. In our experiments a droplet is deposited on a thin layer of particles, at the start of the drop test the droplet jumps from the particle bed in response to the step reduction in gravity. As the droplet leaves the particle bed, it takes a fraction of the particles with it. Droplet jump properties such as contact time and velocity are considered. Characteristics of droplet jump from a particle bed are compared to droplet jump from a superhydrophobic surface.