A molecular dynamics study of surface wettability effects on heterogeneous bubble nucleation

In this paper, the bubble nucleation on ideally smooth surfaces with different wettabilities is investigated by molecular dynamics simulations. Nucleation is induced by raising temperature of solid surface to 160 K while removing the thermostat of the liquid. To fully understand the effect of surface wettability on bubble nucleation, several aspects related to the nucleation process are investigated, including void number, void probability, waiting time and bubble growth rate. It is found that there exists an appropriate range of interaction parameter (0.00624 eV < epsilon(Ar-Pt) < 0.052 eV) between solid and liquid atoms to enable the occurrence of bubble nucleation. Simultaneously, it is found that the initial stage of nucleate boiling can be divided into two stages: slow nucleation stage and rapid growth stage. Furthermore, the probability of void formation above the surface gradually increases with the increase of hydrophobicity of the surface, while the bubble growth rate increase with the increase of hydmphilicity of the surface. Finally, in consideration of the balance between the bubble growth rate and void probability, a mixed-wettable surface is proposed, which is verified to benefit the bubble nucleation at the nanoscale.