Multi-bubble dynamics considering the direction of bubble-bubble interactions under acoustic field excitation

To investigate the influence of bubble-bubble interactions on the vibrational dynamics of multi-bubble systems in cavitation fields, a multi-bubble dynamics model was established based on the Keller-Miksis equation. The interaction term was modified to better reflect the spatial inhomogeneity of the interactions. Numerical simulations of cavitation bubbles were conducted using this theoretical model. The study analyzed the effects of initial bubble radius, external acoustic excitation, inter-bubble distance, relative position, and bubble number on bubble-bubble interactions, radial pulsations, and frequency variations. A 2D Fluent simulation model was developed to observe the cavitation process under acoustic excitation in a three-bubble system. The reliability of the theoretical model was validated by comparing changes in bubble radius and frequency. Results indicated that when the acoustic excitation amplitude significantly exceeded the interaction pressure amplitude, bubble-bubble interactions positively correlated with the amplitude variations of the high-frequency vibration component. When the acoustic excitation amplitude was comparable to the interaction pressure, the strength of bubble-bubble interactions influenced the relative radial vibration amplitude and resonant frequency. Factors like initial bubble radius, acoustic excitation, bubble distance, relative position, and bubble number influence radial vibrations. Due to coupling interactions, the resonant frequency of bubbles in a cluster shifts to lower values. The Fluent simulations confirmed that the theoretical model accurately captured the bubble vibration processes and characteristics.