Sliding, vibrating and swinging droplets on an oscillating fibre

TL;DR

This study experimentally investigates how water droplets behave on an oscillating tilted fibre, revealing various dynamic modes and their impact on droplet sliding speed, with a minimal model explaining the swinging mode as a forced elastic pendulum.

Contribution

It introduces a comprehensive experimental characterization of droplet dynamics on oscillating fibres and proposes a minimal model for the swinging mode as a forced elastic pendulum.

Findings

Multiple droplet dynamic modes identified (harmonic, subharmonic, rocking, swinging)

Droplet sliding speed varies with oscillation parameters

Swinging mode explained by a minimal elastic pendulum model

Abstract

We study experimentally the dynamics of a water droplet on a tilted and vertically oscillating rigid fibre. As we vary the frequency and amplitude of the oscillations the droplet transitions between different modes: harmonic pumping, subharmonic pumping, a combination of rocking and pumping modes, and a combination of pumping and swinging modes. We characterise these responses and report how they affect the droplet's sliding speed along the fibre. The droplet swinging mode is explained by a minimal model making an analogy between the droplet and a forced elastic pendulum.