Dynamics of bubbles spontaneously entering in a tube

TL;DR

This study investigates the spontaneous shrinking of bubbles in a tube, analyzing the dynamics through experiments, mechanical modeling, and numerical simulations to understand the influence of bubble size and soap films.

Contribution

It introduces a combined experimental and theoretical approach to characterize bubble dynamics in tubes, including a new mechanical force balance model and analytical solutions.

Findings

Emptying duration depends on bubble-to-tube diameter ratio.

Number of soap films influences the shrinking process.

Model predictions align with experimental observations.

Abstract

When an open tube of small diameter touches a bubble of a larger diameter, the bubble spontaneously shrinks and pushes a soap film in the tube. We characterize the dynamics for different bubble sizes and number of soap films in the tube. We rationalize this observation from a mechanical force balance involving the Laplace pressure of the bubble and the viscous force from the advancing soap lamellae in the tube. We propose a numerical resolution of this model, and an analytical solution in an asymptotic regime. These predictions are then compared to the experiments. The emptying duration is primarily affected by the initial bubble to tube diameter ratio and by the number of soap films in the tube.