Effects of Surface Wettability on Rapid Boiling and Bubble Nucleation: A Molecular Dynamics Study

ABSTRACT

Molecular dynamics simulation is conducted to study the effects of surface wettability on rapid boiling and bubble nucleation over smooth surface. The simple L-J liquid is heated by smooth metal surface with different conditions of wettability in cuboid simulation box. The results show that surface wettability has significant impact on phase transition of liquid film. When the heating temperature is 200 K, the rapid boiling occurs above strongly hydrophilic and weakly hydrophilic surfaces; however, only slow evaporation phenomenon occurs above weakly hydrophobic surface within 2.5-ns simulation time. The reason is that the interaction between argon and platinum atoms is stronger over hydrophilic surface, which has higher efficiency in heat transfer. Furthermore, based on the difference of surface wettability in heat transfer efficiency, the surface with nonuniform wettability is constructed, and the central region is more hydrophilic than surrounding region. The growing process of bubble nucleus can be completely observed above the more hydrophilic region.

KEY WORDS:

• Bubble nucleation
• rapid boiling
• surface wettability
• molecular dynamics simulation

Nomenclature

 argon

E energy (eV)

FCC face-centered-cubic structure

Pt platinum

 position vector of atom (Å)

 cutoff distance (Å)

 time step (ps)

V volume (nm³)

 velocity vector of atom (Å/ps)

x coordinate in x direction

y coordinate in y direction

z coordinate in z direction

Greek symbols

 potential energy factor to adjust the strength of hydrophilic interaction

 potential energy factor to adjust the attraction for hydrophobic interaction

 length parameter of LJ potential (Å)

 energy parameter of LJ potential (eV)

 potential energy (eV)

Subscripts

 argon

c cutoff

Pt platinum

Additional information

Funding

This work is supported by the National Natural Science Foundation of China (No. 51636006, No. 51606012), the Project of Construction of Innovative Teams and Teacher Career Development for Universities and Colleges under Beijing Municipality (IDHT20170507), and the Program of Great Wall Scholar (No. CIT&TCD20180313).