Freezing-damped impact of a water drop

TL;DR

This study experimentally examines how freezing affects water drop spreading on cold surfaces, revealing that lower temperatures lead to reduced impact extent, which can be modeled using an analogy with viscous boundary layers.

Contribution

It introduces a novel approach to model freezing effects on drop impact as an effective viscosity, simplifying complex thermal dynamics into a scalable framework.

Findings

Freezing reduces the maximum spreading of water drops on cold surfaces.

An analogy with viscous boundary layers allows modeling freezing effects without complex thermal simulations.

Scaling laws for viscous impact are applicable to solidification-influenced impacts.

Abstract

We experimentally investigate the effect of freezing on the spreading of a water drop. Whenever a water drop impacts a cold surface, whose temperature is lower than 0{\deg}C, a thin layer of ice grows during the spreading. This freezing has a notable effect on the impact: at given Reynolds and Weber numbers, we show that lowering the surface temperature reduces the drop maximal extent. Using an analogy between this ice layer and the viscous boundary layer, which also grows during the spreading, we are able to model the effect of freezing as an effective viscosity. The scaling laws designed for viscous drop impact can therefore be applied to such a solidification problem, avoiding the recourse to a full and complex modelling of the thermal dynamics.