Cavitation Mean Expectation Time in a Stretched Lennard-Jones Fluid under Confinement.

Abstract

We investigate the nucleation of cavitation bubbles in a confined Lennard-Jones fluid subjected to negative pressures in a cubic enclosure. We perform molecular dynamics (MD) simulations with tunable interatomic potentials that enable us to control the wettability of solid walls by the liquid, that is, its contact angle. For a given temperature and pressure, as the solid is taken more hydrophobic, we put in evidence, an increase in nucleation probability. A Voronoi tessellation method is used to accurately detect the bubble appearance and its nucleation rate as a function of the contact angle. We adapt classical nucleation theory (CNT) proposed for the heterogeneous case on a flat surface to our situation where bubbles may appear on flat walls, edges, or corners of the confined box. We finally calculate a theoretical mean expectation time in these three cases. The ratio of these calculated values over the homogeneous case is computed and compared successfully against MD simulations. Beyond the infinite liquid case, this work explores the heterogeneous nucleation of cavitation bubbles, not only in the flat surface case but for more complex confining geometries.