NUMERICAL SIMULATIONS OF SOLUBLE BUBBLE DYNAMICS IN ACOUSTIC FIELDS

Acoustic waves in liquids cause appearance, growth and dissolution of bubbles. Various physical and chemical effects related to bubble dynamics have been studied for a long time due to their importance for sonochemical reactors, acoustical cleaning, biomedical applications and more. One of the factors that may affect the self-organization of bubbles in acoustic fields and stable cavitation bubble formation is rectified diffusion. There exist approximate/asymptotic theories of rectified diffusion including a small amplitude approximation pioneered by Hsieh and Plesset and high radial Peclet number approximation of Fyrillas & Szeri, which do not take into account the influence of the small instantaneous mass change of the bubble on its dynamics. The goal of the present study is to check how these theories are good. For this purpose a numerical method based on the model of spherical bubble experiencing strong nonlinear oscillation in an isotropic acoustic field was developed and direct simulations were performed. Computations are accelerated using multicore CPU parallelization, which enable extensive parametric studies and validation of asymptotic methods via direct numerical simulation. Several cases were analyzed in details which show that the effect neglected in the previous studies may contribute to rectified diffusion (e.g. for micron size bubbles in the regime of sonoluminescence).