Vibration-induced evaporation and boiling of water nanofilm on rough surfaces

Abstract

The high-intensity vibration is a promising method to induce atomization due to the prominent acoustothermal effect at nanoscale. Here we investigate the vibration-induced evaporation and boiling performance of the water nanofilm on rough surfaces using the molecular dynamics method. Results show that the acoustothermal atomization of the water nanofilm can be classified into evaporation, nucleate boiling and film boiling. Under the same vibration, the roughness can suppress the evaporation and boiling performance of the water nanofilm. The change of atomization modes depends on the amplitude (A) and frequency (f) of the vibration, which shows little discrepancy between the smooth surface and rough surface. The residual ratio of water molecules is linearly and negatively correlated with Af3/2 when Af3/2 is smaller than the turning point. The intrinsic mechanism of the vibration-induced acoustothermal atomization of water nanofilm is that the water nanofilm is heated by the increases of potential energy from film tensioning and the kinetic energy from viscous dissipation. The weakening of the vibration-induced water nanofilm evaporation and boiling performance for the rough surface is attributed to the reduction of surface hydrophilicity.