![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
Sonoluminescence is light emission associated with the catastrophic collapse of bubble oscillation under ultrasound. Molecular dynamics (MD) simulation of collapsing bubbles with micro- and nano-size equilibrium radii was performed and the results were compared with theoretical calculations. The molecules inside a collapsing gas bubble were modelled as hard spheres, and the instantaneous bubble radius and the bubble wall velocity used in the simulation were obtained from the Keller–Miksis equation with pressure data taken from MD simulation. With a suitable boundary condition at the bubble wall, the MD simulation results for the bubble wall velocity, the gas temperature and pressure around the collapse point for the sonoluminescing bubbles are in acceptable agreement with theoretical predictions. However, these theoretical predictions need validation because estimated thermal conductivity for the gas and liquid were used for the extreme condition achieved at the collapse point. This study also revealed that the collapsing process of a sonoluminescing gas bubble proceeds almost adiabatically.
Acknowledgements
This work has been supported by a grant from the Electric Power Research Institute (EPRI) in the USA, under contract EP-P19394/C9578. The authors would like to acknowledge support from KISTI (Korea Institute of Science and Technology Information) under the ‘Grand Challenge Support Program’ with Dr Sang Min Lee as the technical supporter. The authors also thank Mr Ali Mechentel at IBM for his help in optimization of the MD program. The use of the computing system of the Supercomputing Center is also greatly appreciated. Dr Ki Young Kim and Mr Chansoo Lim have also been supported by the second stage of the BK21 programme. One (H. Kwak) of the authors was also supported from Chung-Ang University Fund for best researchers.