Wetting morphologies on randomly oriented fibers

TL;DR

This paper investigates how liquids wet and form different shapes on two fibers with random orientations, extending existing models to predict various equilibrium morphologies based on fiber geometry and liquid volume.

Contribution

It introduces an analytical model that predicts liquid morphologies on arbitrarily oriented fibers, expanding understanding beyond parallel and crossed fiber configurations.

Findings

Identified three distinct equilibrium morphologies: column, mixed, and drop.

Developed a predictive model based on fiber geometry and liquid volume.

Validated the model with observed morphologies across different configurations.

Abstract

We characterize the different morphologies adopted by a drop of liquid placed on two randomly oriented fibers, which is a first step toward understanding the wetting of fibrous networks. The present work reviews previous modeling for parallel and touching crossed fibers and extends it to an arbitrary orientation of the fibers characterized by the tilting angle and the minimum spacing distance. Depending on the volume of liquid, the spacing distance between fibers and the angle between the fibers, we highlight that the liquid can adopt three different equilibrium morphologies: (1) a column morphology in which the liquid spreads between the fibers, (2) a mixed morphology where a drop grows at one end of the column or (3) a single drop located at the node. We capture the different morphologies observed using an analytical model that predicts the equilibrium configuration of the liquid based on the geometry of the fibers and the volume of liquid.