In this work, the coarse-grained molecular dynamics simulation is employed to study lubricant evolution and depletion when subjected to a moving laser heat source. A layered film structure is formed in the equilibrium lubricant system due to the polar interactions of the lubricant functional end groups with the disk substrate. The lubricant surface morphology and depletion profiles during laser heating are studied. It is shown that the lubricant undergoes severe depletion increasing as the laser heats up with time, resulting in aggravated lubricant diffusion and evaporation. Moreover, the surface temperature profile is examined under a moving laser heat source and it reveals that the increased temperature is centered around the laser beam and quickly decays away from the laser beam. The non-uniform temperature is formed due to heat transfer between heated beads and surrounding beads, which leads to non-uniformity of surface tension and thermocapillary stress, thereby depleting the lubricant away from the scanning laser beam on the disk surface.
