Molecular dynamics simulation of collapsing phase for a sonoluminescing gas bubble in sulfuric acid solutions: A comparative study with theoretical results

Abstract

Sonoluminescence is the light emission associated with the catastrophic collapse of a bubble oscillating under ultrasound. Molecular dynamics (MD) simulation of a collapsing bubble in sulfuric acid solution was pet-formed and the results from the simulation were compared with the theoretical results which are in good agreement with observed ones. The molecules inside the collapsing noble gas bubble were modeled as hard sphere ones and the instantaneous bubble radius and the bubble wall velocity which were used in the simulation were obtained from the Keller-Miksis equation with pressure data taken from MD simulation. One million particles were used in the scaled-down MID simulation of the sonoluminescing bubble with equilibrium radius of 15 mu m having 10(11) molecules. Remarkable agreement between the MD simulation results and theoretical calculation values was obtained for the adiabatic process. However, the heat bath boundary condition yields much shorter thermal spike than the theoretical value even though the peak temperature obtained is similar to the theoretical one.