How a leak can stop itself

TL;DR

This paper investigates how fluid leaks can spontaneously stop through droplet formation and stabilization, revealing the roles of inertia and flow transition in leak arrest.

Contribution

It introduces a new understanding of leak self-arrest mechanisms by combining experimental observations with energetic theory and flow stability analysis.

Findings

Droplet formation opposes leak flow via Laplace pressure.

A stable capping droplet can halt the leak through harmonic oscillations.

Transition from continuous to discrete flow is crucial for leak self-stopping.

Abstract

Small fluid leaks are common and frequently troublesome. We often consider how to stop a leak, but here we ask a different question: how might a leak stop itself? We experimentally study leaking flow transitions from continuous drainage to spontaneous arrest. High-speed imaging reveals that fluid breakup events generate droplets whose Laplace pressures oppose the leak. Early droplets grow unstably, allowing the leak to continue, but ultimately a final capping droplet equilibrates to a stable spherical cap via lightly damped harmonic oscillations. A total energetic theory incorporating both the potential and kinetic energy of attempted capping droplets shows that inertia plays a key role in the leak-stop mechanism. Further experiments examining the stability of rivulet flow in such a system demonstrate that a transition from continuous to discrete flow is an essential prerequisite in determining when a leak can stop itself.