Impulse-driven capillary detachment

TL;DR

This study investigates how impulsive forces at a capillary interface lead to droplet detachment, highlighting the role of the contact line in converting mechanical impulse into capillary deformation.

Contribution

It reveals that the contact line mediates the transfer of impulsive mechanical energy into capillary deformation, controlling droplet detachment in impulsively forced systems.

Findings

Maximum extension before detachment is determined by the work transmitted through the contact line.

Viscous dissipation during filament extension balances the transmitted mechanical work.

The contact line acts as the key pathway for impulse conversion into capillary deformation.

Abstract

Capillary interfaces subjected to impulsive forcing arise in many natural and technological systems, yet the pathway by which rapid substrate motion is converted into droplet detachment remains unclear. Here we study this process in a controlled setting: a liquid droplet resting on a taut wire that is plucked and suddenly released. The resulting transverse wave imparts a brief inertial forcing at the droplet base, initiating rapid stretching that precedes sheet formation and jet breakup. We show that the maximum extension prior to detachment is set by the mechanical work transmitted from the wire through capillary traction at the three-phase contact line, balanced by viscous dissipation during filament extension. This energetic balance identifies the contact line as the pathway by which mechanical impulse is converted into capillary deformation and governs impulsive droplet detachment.