Relaxation of nonspherical sessile drops towards equilibrium

TL;DR

This paper develops a nonlocal theoretical model for the relaxation of nonspherical sessile drops towards equilibrium, accounting for the entire drop geometry and contact line pinning effects, advancing understanding of wetting dynamics.

Contribution

It introduces a novel nonlocal approach to wetting dynamics that considers the whole drop geometry, contrasting with traditional local models.

Findings

Nonlocal model predicts different relaxation behavior compared to local models.

Contact line pinning significantly affects relaxation dynamics.

Model aligns with recent experimental observations.

Abstract

We present a theoretical study related to a recent experiment on the coalescence of sessile drops. The study deals with the kinetics of relaxation towards equilibrium, under the action of surface tension, of a spheroidal drop on a flat surface. For such a nonspherical drop under partial wetting conditions, the dynamic contact angle varies along the contact line. We propose a new nonlocal approach to the wetting dynamics, where the contact line velocity depends on the geometry of the whole drop. We compare our results to those of the conventional approach in which the contact line velocity depends only on the local value of the dynamic contact angle. The influence on drop dynamics of the pinning of the contact line by surface defects is also discussed.