Energy and momentum transfer in an ultrathin liquid film under shear between solid surfaces

Molecular dynamics study has been performed on ultra-thin liquid film sheared between two solid surfaces, which has a direct relation to lubrication. Energy and momentum transfer in the liquid film and at the solid-liquid interface accompanied by viscous heating are analyzed. The system consists of liquid film where molecules are modeled by the Lennard-Jones (12-6) potential and two parallel solid walls having a spacing of several nanometers. The solid walls have a constant temperature and move at a velocity in the opposite directions to each other, which causes a shear in the liquid film. A layered structure has been formed in the liquid by the effect of interaction with solid molecules, in which highly nonequilibrium distribution of thermal energy among the degrees of freedom for molecular motion is observed.