Effect of Heat Loss on Hydrothermal wave Instability in Half-Zone Liquid Bridges of High Prandtl NumberFluid

Abstract

We investigate the effect of heat transfer through a free surface on the primary instability of thermocapillary-driven convection in a geometry of so-called half-zone liquid bridge of high Prandtl number fluid. The target liquid bridge is a straight whose aspect ratio Γ = H/R is mainly kept at 2.0, where H and R are the height and the radius of the bridge, respectively. We focus on the flow fields induced by the instability; it is found that the bifurcation diagram exhibits a significant difference between the cases of the Prandtl number Pr = 16 and 28. The effect of gravity level is also examined in order to discuss qualitatively the induced flow fields after the transition obtained in the ground-based experiments as well as in on-orbit experiments so-called ‘Dynamic Surf’ in the Japan Experiment Module ‘Kibo’ aboard the International Space Station. Keyword(s): Hydrothermal wave instability, Dynamic Surf, Half-zone liquid bridge, High Prandtl number fluid, Heat transfer Received 22 January 2019; Accepted 18 April 2019; Published 30 April 2019