Flow and Heat Transfer Characteristics of Oscillatory Thermo-Capillary Convection in Half Floating Zones

The present study investigates thermo-capillary convective flow phenomena in a half floating zone of high Prandtl number liquid (Pr = 39.3) under microgravity conditions. The spatiotemporal flow structures inside the half floating zone are studied by performing unsteady and three-dimensional computations in a domain consisting of a flat liquid bridge of 5 cSt silicone oil. The liquid zone is held in its position by thermo-capillary forces (surface tension) between two circular, co-axial and differentially heated rods of the similar diameter. Thermal convection equations which govern the convective flow are solved using a commercial software ANSYS Fluent 18.1 which is based on the finite volume method. The well-known transition to oscillatory and three-dimensional flow occurs when the applied thermo-capillary force (temperature difference between the rods) reaches a critical value for the onset of instability. The observed oscillatory thermo-capillary convection in the present case is described by a standing wave of critical azimuthal wave number (m) equal to 2.