Molecular Thermal Phenomena in an Ultrathin Lubrication Liquid Film of Linear Molecules Between Solid Surfaces

Molecular dynamics simulation has been performed on an ultra-thin lubrication liquid film, where the liquid film of diatomic molecules having a thickness of molecular scale (several nanometers) is sheared by two parallel solid walls moving at different speeds. The Couette-like flow is generated and energy conversion from the macroscopic flow energy to thermal energy, which is the viscous heating in a macroscopic sense, occurs in the liquid film. It was observed in the present simulations that the thermal phenomena in the liquid film are far from the macroscopically expected ones; thermal energy is not distributed evenly to each degree of freedom of molecular motion, and energy transfer in the liquid adjacent to the solid surface is contributed by molecular motion in a manner different from those in a bulk liquid.