Nano Sized Bubble Formation, Growth and Collapse in Liquid Water by Central Heating: A Molecular Dynamics Simulation

摘要

Non-equilibrium Molecular Dynamics (NEMD) Simulation has been employed to investigate the nanobubble generation, growth and collapse in liquid water. The center molecules (240 water molecule) of the simulation domain were heated at five different temperatures (400K, 800K, 1500K, 2100K and 2800K) by velocity scaling for a very short period of time and the radius of the nano sized bubble was calculated. At 400K. temperature, no nano bubble is formed but as temperature increases, nano bubble forms and the radius of the nano bubble increases. TIP-3P potential model has been used to predict the structural parameters of water molecules. The SHAKE algorithm has been employed to hold the bonds of O-H and H-O-H as rigid. The results obtained from the simulation were then compared with the results got from Rayleigh-Plesset Equation in order to show the discrepancy of MD simulation and the Hydrodynamic model. The simulation results indicate that Rayleigh-Plesset equation is not valid for prediction the formation, growth and collapse of nano bubble in liquid water because of its uncertainty in predicting the surface tension and ignoring the viscosity.