Collapse of a nanoscopic void triggered by a spherically symmetric traveling sound wave

Molecular-dynamics simulations of the Lennard-Jones fluid (up to 10(7) atoms) are used to analyze the collapse of a nanoscopic bubble. The collapse is triggered by a traveling sound wave that forms a shock wave at the interface. The peak temperature T-max in the focal point of the collapse is approximately Sigma R-0(a), where Sigma is the surface density of energy injected at the boundary of the container of radius R-0 and a alpha approximate to 0.4-0.45. For Sigma = 1.6 J/m(2) and R-0 = 51 nm, the shock wave velocity, which is proportional to root Sigma, reaches 3400 m/s (4 times the speed of sound in the liquid); the pressure at the interface, which is proportional to Sigma, reaches 10 GPa; and T-max reaches 40 000 K. The Rayleigh-Plesset equation together with the time of the collapse can be used to estimate the pressure at the front of the shock wave.