Contact Line Catch Up by Growing Ice Crystals

TL;DR

This study investigates how freezing affects the motion of the contact line in capillary flows, revealing that ice crystal growth can halt spreading by catching up with the contact line, influenced by substrate thermal properties.

Contribution

It provides experimental evidence and modeling of ice crystal growth dynamics that stop droplet spreading, highlighting the role of substrate thermal properties in freezing behavior.

Findings

Ice crystals grow along the substrate during spreading.

Crystal growth velocity matches contact line velocity when spreading stops.

Substrate thermal properties significantly influence the frozen drop size.

Abstract

The effect of freezing on contact line motion is a scientific challenge in the understanding of the solidification of capillary flows. In this letter, we experimentally investigate the spreading and freezing of a water droplet on a cold substrate. We demonstrate that solidification stops the spreading because the ice crystals catch up with the advancing contact line. Indeed, we observe the formation and growth of ice crystals along the substrate during the drop spreading, and show that their velocity equals the contact line velocity when the drop stops. Modelling the growth of the crystals, we predict the shape of the crystal front and show that the substrate thermal properties play a major role on the frozen drop radius