Investigation of water bubble nucleation by using molecular dynamics simulation

Generation of a bubble nucleus is the initial stage of nucleate boiling and an essential part of the nucleate boiling theory. In the present study, the molecular dynamics simulation method is conducted to study the bubble nucleation of water on a grooved copper substrate with hydrophilicity. An idea based on the competition between molecular kinetic energy and molecular potential restriction, corresponding to the motivity and resistance for bubble nucleation at the nanoscale, is extended to identify the intrinsic regime of bubble nucleation of water. If a group of water molecules obtain enough kinetic energy such that their potential restriction is broken and become activated molecules at some time, the bubble nucleus is taken shape. Simulation results of bubble nucleation behaviors on the substrate with different sizes of grooves indicate that this idea works well in clarifying the intrinsic regimes of bubble nucleation and the nucleation difference between different cases. In addition, this idea can be used to obtain the incipient nucleation position, nucleation time, and the volume of the bubble nucleus without any subjective threshold.