Nucleate boiling of thin liquid films on nanostructured surfaces with hybrid wettability using molecular dynamics simulation

The development in nanotechnology and bionics has increased the application of hybrid wettable nanos-tructured surfaces in engineering and science research. This study employed molecular dynamics to investigate the phase changes of thin liquid films on nanostructured surfaces with hybrid wettability. The liquid film and nanostructured surfaces were consisted of Lennard-Jones (LJ) fluid and LJ solid atoms, respectively. The simulation results indicate that the microscopic mechanism of nucleate boiling is facil-itated by the original residual vapor nuclei. Additionally, the competition mechanism between the hybrid surface wettability and nanostructure is identified. The initial nucleation temperature for a solid wall with a hydrophobic nanocavity is 1.09e/kB, which is 0.04e/kB less than that for a hydrophilic nanocavity. This phenomenon can be attributed to the original residual vapor nuclei generated by hydrophobic nanocavities, which induce a piston-like effect at the vapor-liquid interface. As the nanocavity hydropho-bicity increases, the piston-like effect increases the internal vapor pressure within the cavity and reduces the initial waiting time for bubble nucleation. For the hydrophilic nanocavities with contact angles greater than 18 degrees, the bubbles are initially generated on the smooth surface rather than the nanocavity. Moreover, the smooth surface wettability is instrumental in bubble nucleation and growth. When the contact angle of the nanocavity is less than 18 degrees, the nanostructures are dominant, and the bubbles are generated only in the nanocavity. These findings can aid the design, manufacture, and performance opti-mization of micro/nano-systems and devices.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The study employed molecular dynamics to investigate phase changes of thin liquid films on nanostructured surfaces with hybrid wettability. Results show that the original residual vapor nuclei facilitate the mechanism of nucleate boiling, and competition mechanism between liquid film and nanostructure was identified. Hydrophobic nanocavities induce a piston-like effect, reducing the waiting time for bubble nucleation and being more effective in bubble generation compared to hydrophilic nanocavities.