A molecular dynamics investigation on evaporation of thin liquid films

摘要

Understanding of evaporation process of thin liquid film is important for studying heat transfer near the triple-phase contact line. In the present work, equilibrium molecular dynamics (EMD) and non-equilibrium molecular dynamics (NEMD) were employed to investigate the evaporation of thin liquid films in a nanoscale triple-phase system. The simulation domain was a cuboid, which consisted of an upper and a lower platinum wall, with argon fluid in between. The solid walls were first set at the same temperature and EMD was employed to achieve an equilibrium state. Then the walls were set at different temperatures and NEMD was employed to simulate the non-equilibrium state. Evaporation and condensation of thin liquid films were observed. The evolution of the film thickness as well as the net mass flux was obtained for the evaporating thin film. Interfacial accommodation coefficient was analyzed and the measured evaporation mass flux was compared with Hertz-Knudsen-Schrage equation which is based on kinetic theory of gases (KTG). Non-evaporating layer due to strong intermolecular forces was obtained and compared with theoretical models.