Drop on a Bent Fibre

TL;DR

This paper investigates how bent fibres can hold more water than horizontal ones, revealing the optimal bending angle and developing models to predict water retention, with applications in microfluidics and fog harvesting.

Contribution

It introduces the concept that fibre bending significantly enhances water retention, providing experimental data and models to optimize fibre design for fluid capture.

Findings

Bent fibres hold up to three times more water than horizontal fibres.

Optimal bending angle for maximum water retention is approximately 36 degrees.

Models accurately predict the maximum water volume based on fibre angle and surface tension.

Abstract

Inspired by the huge droplets attached on cypress tree leaf tips after rain, we find that a bent fibre can hold significantly more water in the corner than a horizontally placed fibre (typically up to three times or more). The maximum volume of the liquid that can be trapped is remarkably affected by the bending angle of the fibre and surface tension of the liquid. We experimentally find the optimal included angle ($\sim {36}{^\circ}$) that holds the most water. Analytical and semi-empirical models are developed to explain these counter-intuitive experimental observations and predict the optimal angle. The data and models could be useful for designing microfluidic and fog harvesting devices.