Evaporation of liquid coating a fiber

TL;DR

This paper combines theoretical analysis and numerical simulations to study the evaporation behavior of liquids on fibers, revealing how geometry influences evaporation flux and rate, with implications for coating and drying processes.

Contribution

It provides new analytical and numerical insights into how fiber geometry affects liquid evaporation, especially the flux divergence and volume-independent evaporation rates.

Findings

Flux diverges at edges with increasing aspect ratio

Evaporation rate is nearly independent of wetting properties for large droplets

Droplets evaporate as spheres of the same volume regardless of wetting

Abstract

We investigate theoretically and numerically the diffusion-limited evaporation of a liquid deposited on a fiber in two configurations: a sleeve and a axisymmetric barrel-shaped droplet. For a sleeve, the local flux depends on both the aspect ratio and the smallest length of the problem. By using analytical calculations and 3D finite elements simulations, we predict a divergence of this flux further localized at the edge as the aspect ratio increases. The evaporation of axisymmetric drops on a fiber is studied with numerical simulations. For sufficiently large volumes, we evidence that the evaporation rate is almost independent of the wetting properties of the liquid, even for small contact angles, and that the droplets evaporate as spheres of the same volume.