Manipulating air bubbles with secondary Bjerknes forces

Abstract

Gas bubbles in a sound field are submitted to a radiative force, known as the secondary Bjerknes force. In this presentation, we propose an original experimental setup that allowed us to investigate in details this force between two neighboring bubbles. The dependance with the sonication frequency, as well as the bubbles radii and distance, was examined. We report the observation of both attractive and, more interestingly, repulsive Bjerknes force, when the two bubbles have different radii and can thus be driven in antiphase. On the contrary, our results also show the importance of taking multiple scattering into account when the bubbles radii become similar. The 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.