Drop splashing is independent of substrate wetting

TL;DR

This study demonstrates that the splashing of liquid drops upon impact is unaffected by substrate wetting properties at high capillary numbers, challenging existing theories linking wetting to splashing behavior.

Contribution

The paper provides experimental and numerical evidence showing splashing independence from wettability, contradicting prior predictions based on forced wetting similarities.

Findings

Wetting properties do not influence splashing at high capillary numbers.

The shape and motion of the air-liquid interface are independent of wettability.

Existing theories predicting wetting dependence are not supported by the data.

Abstract

A liquid drop impacting a dry solid surface with sufficient kinetic energy will splash, breaking apart into numerous secondary droplets. This phenomenon shows many similarities to forced wetting, including the entrainment of air at the contact line. Because of these similarities and the fact that forced wetting has been shown to depend on the wetting properties of the surface, existing theories predict splashing to depend on wetting properties as well. However, using high-speed interference imaging we observe that at high capillary numbers wetting properties have no effect on splashing for various liquid-surface combinations. Additionally, by fully resolving the Navier-Stokes equations at length and time scales inaccessible to experiments, we find that the shape and motion of the air-liquid interface at the contact line at the edge of the droplet are independent of wettability. We use these findings to evaluate existing theories and to compare splashing with forced wetting.