Molecular dynamics analysis for the effect of the wettability and the slip on the solid wall surface on bubble growth

Abstract

Since the boiling heat transfer is much affected by the nucleation of bubble and its growth, estimation of such process is essential for the accurate prediction of the heat transfer. In this study, molecular dynamics simulations were performed in order to clarify the effect of the wall conditions, i.e. the wettability and the slip between fluid and solid wall, on the bubble growth. The simulation results show that the evaporation near the contact line is enhanced and the vapor jet from contact line is observed. The direction of the vapor jet from the contact line is along the solid wall surface in the case of large slip and is along the liquid-gas interface in the case of small slip. The difference in the direction of the vapor jet is due to the flow in the adsorption layer on solid wall surface (in solid-gas interface). In the case of large slip, the fluid molecules in the adsorption layer flow with larger velocity in the direction away from the contact line. The vapor jet thus can develop along the surface of the adsorption layer. In the case of small slip, by contrast, the flow in the adsorption layer is prevented by the wall shear stress and the layer held on the wall surface invokes shear stress between the layer and the vapor jet. Consequently, the slip affects the vapor jet from contact line.

Keywords

• contact line
• wettability
• slip
• evaporation
• interface
• nonequilibrium molecular dynamics simulation