Maximum speed of dewetting on a fiber

TL;DR

This paper theoretically analyzes the maximum speed at which a nonwetting liquid can dewet from a fiber, revealing how fiber radius influences the transition and meniscus profile stability.

Contribution

It derives the maximum dewetting speed using asymptotic expansion and explores bifurcation diagrams for steady menisci on fibers of different radii.

Findings

Maximum dewetting speed occurs at zero apparent contact angle.

Thick fibers have smooth meniscus profiles even with deposited films.

Thin fibers exhibit oscillatory meniscus profiles.

Abstract

A solid object can be coated by a nonwetting liquid since a receding contact line cannot exceed a critical speed. We theoretically investigate this forced wetting transition for axisymmetric menisci on fibers of varying radii. First, we use a matched asymptotic expansion and derive the maximum speed of dewetting. For all radii we find the maximum speed occurs at vanishing apparent contact angle. To further investigate the transition we numerically determine the bifurcation diagram for steady menisci. It is found that the meniscus profiles on thick fibers are smooth, even when there is a film deposited between the bath and the contact line, while profiles on thin fibers exhibit strong oscillations. We discuss how this could lead to different experimental scenarios of film deposition.