Weak-inertial effects on destabilized receding contact lines

TL;DR

This paper investigates how inertia affects the shape and stability of receding contact lines beyond the critical speed, providing inertial corrections to existing models and revealing increased film thickness and cusp-like interface shapes.

Contribution

It introduces the leading-order inertial correction to the classical self-similar contact line solution, accounting for inertia's role near the critical destabilization speed.

Findings

Inertia causes the interface to become cusp-like with increased film thickness.

Inertial effects scale with the capillary number and modify the flow and interface shape.

Inclusion of contact line dynamics shows increased inertial contribution with speed despite confinement.

Abstract

It is known that beyond a critical speed, the straight contact line of a partially-wetting liquid destabilizes into a corner. In one of the earliest theoretical works exploring this phenomenon, [L. Limat and H. A. Stone, Europhys. Lett. 65(3), 2004] elicited a self-similar conical structure of the interface in the viscous regime. However, noting that inertia is not expected to be negligible at contact line speeds close to, and beyond the critical value for many common liquids, we provide the leading-order inertial correction to their solution. In particular, we find the self-similar corrections to the interface shape as well as the flow-field, and also determine their scaling with the capillary number. We find that inertia invariably modifies the interface into a cusp-like shape with an increased film thickness. Furthermore, when incorporating contact line dynamics into the model, resulting in a narrowing of the corner as the contact line speed increases, we still observe an overall increase in the inertial contribution with speed despite the increased confinement.