Bubble formation on solid surface with a cavity based on molecular dynamics simulation

• Bubble formation of Ar on Pt surface with a cavity is studied by MD simulation.
• The cavity enhances bubble formation significantly with different argon density.
• Argon in the cavity experiences large density, repulsive force and energy gradients.
• Cavity and smooth surfaces are compared with different surface wettabilities.
• Argon atoms are solid-like in the cavity with all the hydrophilic surfaces.

In this paper, molecular dynamics simulations are conducted to analyze the bubble formation in liquid argon on a platinum surface with a cavity. Comparisons are made between the channels with and without the cavity on the lower wall; varying argon densities and surface wettabilities are also examined. The cavity on the surface can significantly enhance the growth of the bubble. The argon atoms in the cavity experience large repulsive forces, repulsive force gradients, density gradients and potential energy along the z axis, which are much larger than those near the plane surface. The argon atoms at the bottom of the cavity seem to be crystallized with all the hydrophilic surfaces, while for the argon atoms near the plane surface, they are solid-like with the strong hydrophilic surface and fluid-like with the weak hydrophilic surface. For the hydrophobic surfaces, there are few atoms in the cavity, and large fluctuations of density are observed near the surface. The plane surface shows almost the same density distributions as the cavity surface, and the surface feature seems to be irrelevant to the bubble formation.