The role of drop shape in impact and splash

TL;DR

This study investigates how non-spherical drop shapes, created using ferrofluids, influence impact and splash behavior, revealing universal mechanisms and potential for controlling splash outcomes beyond traditional spherical models.

Contribution

It introduces the impact of drop shape on splash dynamics, demonstrating universal mechanisms and expanding impact research beyond spherical drops using ferrofluid experiments.

Findings

Drop shape significantly affects spreading and splash dynamics.

Universal impact mechanisms include superellipse model and Kelvin-Helmholtz instability.

Splash amount is linked to energy dissipation before liquid takes off.

Abstract

The impact and splash of liquid drops on solid substrates are ubiquitous in many important fields. However, previous studies have mainly focused on spherical drops while the non-spherical situations, such as raindrops, charged drops, oscillating drops, and drops affected by electromagnetic field, remain largely unexplored. Using ferrofluid, we realize various drop shapes and illustrate the fundamental role of shape in impact and splash. Experiments show that different drop shapes produce large variations in spreading dynamics, splash onset, and splash amount. However, underlying all these variations we discover universal mechanisms across various drop shapes: the impact dynamics is governed by the superellipse model, the splash onset is triggered by the Kelvin-Helmholtz instability, and the amount of splash is determined by the energy dissipation before liquid taking off. Our study generalizes the drop impact research beyond the spherical geometry, and reveals the potential of using drop shape to control impact and splash.