Depinning of three-dimensional drops from wettability defects

TL;DR

This paper investigates how three-dimensional liquid drops detach from substrate defects, revealing that depinning transitions explain observed stick-slip motion, with implications for understanding wetting and sliding behavior.

Contribution

It introduces a long-wave evolution model to analyze depinning of 3D drops from wettability defects, elucidating the transition mechanisms.

Findings

Depinning transition explains stick-slip motion.

Hydrophilic and hydrophobic defects influence depinning behavior.

A long-wave model effectively describes the dynamics.

Abstract

Substrate defects crucially influence the onset of sliding drop motion under lateral driving. A finite force is necessary to overcome the pinning influence even of microscale heterogeneities. The depinning dynamics of three-dimensional drops is studied for hydrophilic and hydrophobic wettability defects using a long-wave evolution equation for the film thickness profile. It is found that the nature of the depinning transition explains the experimentally observed stick-slip motion.