Thermocapillary Convection in a Liquid Layer with a Quasi-Point Heat Source in the Substrate

By the method of tracer particles the velocity field of thermocapillary convection in a thin layer of silicone oil, excited by a quasi-point heat source in the rigid substrate, is investigated as a function of the layer thickness, the temperature of the heater, and the liquid viscosity. The vertical velocity distributions are plotted in several cross-sections at different distances from the vortex axis. A novel method of measuring the profile of the thermocapillary depression, based on mirror reflection from the free liquid surface of radiation scattered by a tracer particle, is proposed. The central segment of the profile of the thermocapillary depression is obtained for different values of the layer thickness, the liquid viscosity and the heater temperature.