Corona splashing triggered by a loose monolayer of particles

TL;DR

This study investigates how a loose monolayer of particles influences the splash behavior of high-speed raindrops, revealing that mobile particles lower the impact velocity needed for corona splashing, with implications for soil erosion.

Contribution

It combines experimental and mathematical methods to show that particle mobility and packing density affect droplet splashing dynamics on particulate surfaces.

Findings

Mobile particles lower the critical impact velocity for splashing.

Increased particle area fraction enhances splash likelihood.

Jamming of particles at the spreading rim explains the transition.

Abstract

In nature, high-speed raindrops often impact and spread on particulate surfaces (e.g., soil, plant leaves with spores or pollen). We study the dynamics of droplet impact on a loosely packed monolayer of particles by combining experimental and mathematical approaches. We find that the presence of mobile particles lowers the critical impact velocity at which the droplet exhibits corona splashing, as the particle area fraction is systematically increased. We rationalize this experimental observation by considering the jamming of frictional particles at the spreading rim. Elucidating the splashing transition of the drop on a particulate bed can lead to a better understanding of soil loss and erosion from falling raindrops.