Nonspherical armoured bubble vibration

TL;DR

This study investigates how cylindrical armoured bubbles transition to spherical shapes under mechanical vibrations, revealing metastability and potential for controlled particle dissemination with minimal energy input.

Contribution

It demonstrates the metastable nature of nonspherical armoured bubbles and details the energy dynamics involved in their shape transition and particle release.

Findings

Nonspherical bubbles are metastable states.

Vibration energy can induce shape transition.

Particle desorption requires overcoming capillary forces.

Abstract

In this paper, we study the dynamics of cylindrical armoured bubbles excited by mechanical vibrations. A step by step transition from cylindrical to spherical shape is reported as the intensity of the vibration is increased, leading to a reduction of the bubble surface and a dissemination of the excess particles. We demonstrate through energy balance that nonspherical armoured bubbles constitute a metastable state. The vibration instills the activation energy necessary for the bubble to return to its least energetic stable state: a spherical armoured bubble. At this point, particle desorption can only be achieved through higher amplitude of excitation required to overcome capillary retention forces. Nonspherical armoured bubbles open perspectives for tailored localized particle dissemination with limited excitation power.