Effect of non-equilibrium evaporation and condensation on bubble dynamics near the sonoluminescence threshold

Abstract

The kinetic equation of evaporation and condensation of water vapour at the bubble wall is calculated numerically in order to investigate the non-equilibrium effect of evaporation and condensation. The liquid temperature at the bubble wall is also calculated as a function of time by estimating the heat flux at the bubble wall. Calculations are performed under a single-bubble sonoluminescence condition. It is clarified that the partial pressure of water vapour is identical to the saturated vapour pressure except at bubble collapse. At a strong collapse, the partial pressure of water vapour differs an order from the saturated vapour pressure of the heated liquid layer at the bubble wall. It is also clarified that most of all the vapour molecules (H 2O) undergo chemical reactions at the strong collapse.