Mesoscopic simulations of cavitation and vapor bubble development

Cavitation occurs as the pressure is reduced below the saturated vapor pressure, but often a substantial negative pressure is needed in a pure liquid. Classical nucleation theory (CNT) provides an estimate for the rate of cavitation but there is often a disconnect between the predictions at the molecular scale compared to that observed at the macroscale. We report on mesoscopic simulations of cavitation based on multibody dissipative particle dynamics (mDPD), a coarse-grained MD. The liquid is confined in a layer between planar walls at a constant temperature, while the pressure is reduced slowly by expanding the wall-bounded domain. The wetting properties of the liquid are determined by the parameters of the interaction potentials. With hydrophilic walls, we observe homogeneous nucleation at conditions comparable to those for a Lennard-Jones liquid. As a bubble forms and grows it creates a strong pressure pulse and oscillations that causes other bubbles that may have formed slightly later to collapse. For a neutral wall, contact angle 90°, heterogeneous nucleation occurs at the walls at a smaller negative pressure. For a superhydrophobic wall, heterogeneous nucleation occurs easily at the walls with minimal pressure oscillations or pulses, with bubbles growing to form a vapor film.