Article
Bubble cluster structure dynamics under strong acoustic driving (en)
* Presenting author
Abstract:
In this study, we examine the dynamics of a cluster of initially uniformly arranged bubbles within a cylindrical volume under the influence of intense acoustic excitation in a phosphoric acid solution. Here, we captured high-speed video recordings of the temporal evolution of bubble clouds generated by laser pulses of different energies, beam diameters, and at variable acoustic driving intensities. The videos revealed significant interactions among individual bubbles, resulting in the formation of multiple smaller clusters. These sub-clusters move away from the region of maximum acoustic pressure, creating well-defined streamers. We extracted the temporal changes the average maximum bubble radius, the void fraction, and the pressure amplitude, for various experimental scenarios. These parameters were used in hybrid numerical simulations of the cluster dynamics. The model accounts for bubble coupling in Keller-Miksis equations, and sound propagation via Louisnard’s modified Helmholtz equation which accounts for the non-linear nature of the acoustic field. The model allowed us to analyse the influence of bubble coalescence, bubble-bubble interactions, and the primary acoustic forces on the collective behaviour of the bubble cluster. The findings of this study represent a significant step toward creating more realistic numerical models, which could contribute to the design of sonochemical reactors.