The motion of a droplet placed in a gas phase near an evaporating, planar liquid-gas interface is considered. Due to latent heat of evaporation, the gradients of temperature and vapor concentration are sustained in the system. The temperature gradient results in the thermocapillary force acting on the droplet and on the planar liquid-gas interface causing thermocapillary flows in the three phases. The corresponding hydrodynamic and diffusion problems are solved using bispherical coordinates, and the velocity of the droplet as a function of the drop separation distance from the interface is found. It is shown that, in the absence of gravity, there exists a critical separation distance above which the drop escapes from the interface and below which the drop is captured by the interface. In the presence of gravity, it is shown that there exists a steady-state separation distance at which the drop can levitate above the interface.
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