Moving contact line of a volatile fluid

TL;DR

This paper investigates the microscopic dynamics of a volatile fluid's moving contact line, deriving how substrate temperature influences the apparent interface slope and regularization length through the Kelvin effect.

Contribution

It introduces a model linking substrate temperature to the Voinov angle and length for volatile fluids, advancing understanding of microscopic effects at the contact line.

Findings

Voinov angle and length depend on substrate temperature.

Kelvin effect controls evaporative/condensation flux at the contact line.

Model predictions are relevant for experimental applications.

Abstract

Interfacial flows close to a moving contact line are inherently multi-scale. The shape of the interface and the flow at meso- and macroscopic scales inherit an apparent interface slope and a regularization length, both called after Voinov, from the dynamical processes at work at the microscopic level. Here, we solve this inner problem in the case of a volatile fluid at equilibrium with its vapor. The evaporative/condensation flux is then controlled by the dependence of the saturation temperature on interface curvature -- the so-called Kelvin effect. We derive the dependencies of the Voinov angle and of the Voinov length as functions of the substrate temperature. The relevance of the predictions for experimental problems is finally discussed.