Increased solidification delays fragmentation and suppresses rebound of impacting drops

TL;DR

This study investigates how solidification within impacting drops on sublimating dry ice influences rebound and fragmentation, revealing that solidification thickness, impacted by velocity, controls impact outcomes and can suppress rebound entirely.

Contribution

It introduces the role of internal solidification in drop impact dynamics on sublimating surfaces and develops a thermo-elastocapillarity framework to predict impact regimes.

Findings

Solidification thickness depends on impact velocity.

Solidification suppresses rebound and delays fragmentation.

Impact outcomes range from complete rebound to no rebound.

Abstract

The splat formed after drop impact on supercooled solid surfaces sticks to it. On the contrary, a sublimating supercooled surface such as dry ice inhibits pinning and therefore efficiently rebounds drops made of a variety of liquids. While rebound is expected at lower impact velocities on dry ice, at higher impact velocities the drop fragments leaving behind a trail of smaller droplets. However, it is not known whether rebound can be entirely suppressed or fragmentation be controlled on such surfaces and if it depends on the extent of solidification inside the drop. In this work, we report on the role played by solidification within drops in modifying the outcomes of their impact on the supercooled ultra-low adhesive surface of sublimating dry ice. We show that the solidification thickness depends on the impact velocity and is the primary driver in suppression of rebound and also promotes a delay in fragmentation. Our findings imply that sublimating supercooled surfaces can present a broad spectrum of outcomes from complete bouncing to no-rebound which are not seen in drop impacts on supercooled superhydrophobic surfaces. We attribute this to thermo-elastocapillarity which considers bending of the solidified layer and is used to demarcate regime boundaries and determine the coefficient of restitution during rebound.