Jetting from an impacting drop containing a particle

Abstract

We investigate the dynamics of a drop containing a single solid particle impacting on a solid surface. The particle rebounds through the drop during impact and can separate from the deposited liquid above an impact velocity threshold. We show that this threshold can be predicted by a simple energy balance. Moreover, we discover a new type of liquid jetting ejected above the particle faster than the impact velocity. We demonstrate that this jetting is due to the focusing effect of the liquid on the solid substrate below the rebounding particle. Although the wetting properties of the particle have a minor effect on the separation threshold, they play a key role in the liquid jetting by affecting the immersion depth of the particle at the time of impact.