The Collapse of Nanobubbles in Water

摘要

The coalescence of bubbles bears on several practical aspects,such as propellers erosion,the generation of luminescence,and a special case of chemical reactivity.Bubbles were advocated to drive microfluidic transport,and their presence was reported in atomic force microscopy experiments.The description of bubble collapse has long been done in terms of hydrodynamics.Information on the collapse is obtained usually through sonoluminescence experiments.Theoretically,analytical models and semianalytic solutions of the dynamics of collapse have appeared,together with atomistic simulations with simple Lennard-Jones potentials.The appearance of cavities has been studied by molecular dynamics simulations.The present molecular dynamics simulations of bubble collapse were performed for the idealized cavity with a radius of 1 nm (an additional calculation was performed for a radius of 1.5 nm) at constant pressure of 1 atm.During the collapse,the system was not coupled to a thermal bath,and temperature was allowed to vary freely.Water was described by the SPC model.All simulations were carried out with the TINKER package.Bubbles were created inside cubic boxes with up to 3000 water molecules.The systems were equilibrated in the presence of a Lennard-Jones potential at their center with a collision radius of 1 (or 1.5) nm.