Rarefied gas correction for the bubble entrapment singularity in drop impacts

TL;DR

This paper investigates how rarefied gas effects, specifically slip corrections, influence the singular behavior during drop impact on a solid surface, potentially explaining experimental observations of gas pressure effects.

Contribution

It introduces a first-order correction to drop impact dynamics by incorporating slip conditions in the gas layer, revealing new regimes that reduce singularity strength.

Findings

Different dynamical regimes reduce impact singularity

Slip effects alter gas entrapment dynamics

Potential link to experimental gas pressure effects

Abstract

We study the non-continuous correction in the dynamics of drop impact on a solid substrate. Close to impact, a thin film of gas is formed beneath the drop so that the local Knudsen number is of order one. We consider the first correction to the dynamics which consists of allowing slip of the gas along the substrate and the interface. We focus on the singular dynamics of entrapment that can be seen when surface tension and liquid viscosity can be neglected. There we show that different dynamical regimes are present that tend to lower the singularity strength. We finally suggest how these effects might be connected to the influence of the gas pressure in the impact dynamics observed in recent experiments.