Manipulating bubbles with secondary Bjerknes forces

TL;DR

This paper presents an experimental study of secondary Bjerknes forces between bubbles, revealing both attractive and repulsive interactions influenced by frequency, bubble size, and distance, with implications for non-contact microfluidic manipulation.

Contribution

The study introduces a novel experimental setup to precisely investigate secondary Bjerknes forces, including repulsive interactions, and highlights the significance of multiple scattering effects.

Findings

Observation of both attractive and repulsive Bjerknes forces.

Strong acoustic coupling when bubbles have similar radii.

Potential applications in non-contact microfluidic manipulation.

Abstract

Gas bubbles in a sound field are submitted to a radiative force, known as the secondary Bjerknes force. We propose an original experimental setup that allows us to investigate in details this force between two bubbles, as a function of the sonication frequency, as well as the bubbles radii and distance. We report the observation of both attractive and, more interestingly, repulsive Bjerknes force, when the two bubbles are driven in antiphase. Our experiments show the importance of taking multiple scattering into account, which leads to a strong acoustic coupling of the bubbles when their radii are similar. Our setup demonstrates the accuracy of secondary Bjerknes forces for attracting or repealing a bubble, and could lead to new acoustic tools for non contact manipulation in microfluidic devices.