Self-motion of a camphor disk coupled with convection

The self-motion of a camphor disk on water was investigated both experimentally and theoretically. When the camphor disk moved along a one-dimensional water chamber, a convective flow was observed around the disk and the magnitude of convection decreased with an increase in the velocity of camphor motion. The camphor disk exhibited a characteristic motion that depended on the shape of the base of the chamber. The nature of the self-motion was reproduced by a numerical simulation that included the surface tension of the camphor layer as the driving force and Marangoni convection induced by the difference in surface tension around the camphor disk.