Gas-Phase Mass Segregation in Acoustic Cavitation at Audible Frequencies*

We present an efficient reduced-order model for simulating mass segregation in acoustically collapsing bubbles. The model has been derived by adopting an ansatz for the functional form of the concentration profiles of the species in the gas mixture and accounts for non-equilibrium at the bubble interface. We validate our results against the solution of the advection-diffusion equation and compare them against those obtained by the boundary layer model, extensively used to predict vapor segregation in sonoluminescing bubbles. Obtained in an order of magnitude less computational time, results from our model are very close to those of the advection-diffusion equation in a wide parameter range, well beyond the applicability of the boundary layer method. The better agreement of our model with the advection-diffusion equation is achieved through a more accurate description of both non-equilibrium phase-change dynamics at the bubble wall and the mass transport profiles inside the bubble.