Splash control of drop impacts with geometric targets

TL;DR

This study demonstrates that the shape and stability of splashes from impacting drops can be controlled by the geometry of the target surface, affecting lamella expansion and breakup patterns.

Contribution

It introduces a method to manipulate splash dynamics through geometric target design, revealing the influence of target shape on splashing behavior.

Findings

Geometric targets alter lamella shape and breakup patterns.

Target geometry influences transition from regular to irregular splashing.

Azimuthal perturbations and Plateau-Rayleigh instability govern splash behavior.

Abstract

Drop impacts on solid and liquid surfaces exhibit complex dynamics due to the competition of inertial, viscous, and capillary forces. After impact, a liquid lamella develops and expands radially, and under certain conditions, the outer rim breaks up into an irregular arrangement of filaments and secondary droplets. We show experimentally that the lamella expansion and subsequent break up of the outer rim can be controlled by length scales that are of comparable dimension to the impacting drop diameter. Under identical impact parameters, ie. fluid properties and impact velocity, we observe unique splashing dynamics by varying the target cross-sectional geometry. These behaviors include: (i) geometrically-shaped lamellae and (ii) a transition in splashing stability, from regular to irregular splashing. We propose that regular splashes are controlled by the azimuthal perturbations imposed by the target cross-sectional geometry and that irregular splashes are governed by the fastest-growing unstable Plateau-Rayleigh mode.