Vapor bubble nucleation by rubbing surfaces: Molecular dynamics simulations

We propose a new mechanism for bubble nucleation triggered by the rubbing of solid surfaces immersed in a liquid, in which the fluid molecules squeezed between the solids are released with high kinetic energy into the bulk of the liquid, resulting in the nucleation of a vapor bubble. Molecular dynamics simulations with a superheated Lennard-Jones fluid are used to evidence this mechanism. Nucleation is observed at the release of the squeezed molecules, for squeezing pressures above a threshold value and for all the relative velocities between the solids that we investigate. We show that the total kinetic energy of the released molecules for a single release event is proportional to the number of molecules released, which depends on the squeezing pressure, but is independent of the velocity.