Velocity Field of Thermocapillary Convection in High Temperature Oxide Solution

We have investigated experimentally and theoretically the thermocapillary convective flow phenomena in a loop-shaped Pt wire heater of KNbO₃(20wt.%) and Li₂B₄O₇ solution. Optical evaluations in connection with thermocouple measurements made it possible to get a new type of thermocapillary convective flow in the considered system. To study the kinematical behavior of thermocapillary convection, we have measured the stream velocities of flow. In a theoretical analysis, the flow velocity due to thermocapillary effect alone was estimated by balancing the surface tension forces by viscous forces. The velocity distribution in the solution near the margin of the heater was obtained, which is in agreement with the experimental result.