Mechanisms of mass transfer effect for the vapor-gas bubble under acoustic excitation

This paper theoretically explores the mechanisms of the mass transfer effect for the vapor-gas bubble under acoustic excitation. The mathematical model for the mixture bubble mass transfer is established based on the perturbation method. The threshold of the mixture bubble under different vapor mass fractions is compared with those of the gas bubble. The threshold represents the amplitude condition at which the molar quantity of gas within the bubble achieves the dynamic equilibrium state, which dictates whether the bubble expands or contracts. The main conclusions are summarized as follows: (1) The vapor mass fraction inside the mixture bubble has a significant effect on the mass transfer processes, including bubble growth, gas diffusion, and convection. (2) As the initial valor mass fraction increases, the resonance region moves in the direction of a decreasing equilibrium radius. In the region far above resonance, threshold curves of the mixture bubble show either an upward trend or a downward trend. (3) The bubble radius, vapor mass fraction, and threshold value all undergo variations during the mixture bubble's growth or shrinkage processes.