SONOLUMINESCENCE AND DIFFUSIVE TRANSPORT

A new model is presented for the gas dynamics within a bubble at condi tions that lead to the phenomenon of sonoluminescence. The spherically symmetric Navier-Stokes equations with variable properties are solved together with momentum and energy equations in the liquid. Calculatio ns are presented for bubbles of argon, helium, and xenon in liquid wat er. The first main result is that in contrast to recent models of air bubbles in water, there are no sharp shocks focusing at the origin of the bubble. An alternative mechanism for energy focusing in noble gas bubbles is proposed that is consistent with a smooth onset of sonolumi nescence with increasing acoustic forcing, as observed in experiments. The second main result concerns an observed correlation between sonol uminescence intensity and the thermal conductivity of the gas, which s uggests that heat transfer plays a dominant role in the focusing of ac oustic energy. It is shown instead that mechanical effects associated with the molecular mass of the gas figure prominently in determining t he peak temperatures and pressures in the bubble, when the bubble is f orced strongly enough to engender wavy disturbances that focus on the bubble center. (C) 1996 American Institute of Physics.