Sensitivity of hydrothermal wave instability of Marangoni convection to the interfacial heat transfer in long liquid bridges of high Prandtl number fluids

• Published in: Physics of fluids (1994) 2017-04, Vol.29 (4)
• Main Authors: Yano, T., Nishino, K., Ueno, I., Matsumoto, S., Kamotani, Y.
• Format: Article
• Language: English
• Subjects: Aspect ratio; Computational fluid dynamics; Fluid dynamics; Heat transfer; Interface stability; International Space Station; Liquid bridges; Marangoni convection; Microgravity; Physics; Prandtl number; Sensitivity; Stability analysis
• ISSN: 1070-6631; 1089-7666
• DOI: 10.1063/1.4979721

This paper reports the sensitivity of hydrothermal wave (HTW) instability of Marangoni convection to the interfacial heat transfer in liquid bridges (LBs) of high Prandtl number fluids (Pr = 67, 112, and 207) formed under the microgravity environment on the International Space Station. The data for instability are collected for a wide range of AR and for T C = 15 and 20 °C, where AR is the aspect ratio (=height/diameter) of the LB and T C is the cooled disk temperature. A significant decrease in critical oscillation frequency as well as an appreciable decrease in the critical Marangoni number is observed for AR > 1.25. This drastic change of instability mechanisms is associated with the reversal of axial traveling direction of HTWs and roll-structures as reported previously. It is found that this reversal is closely related to the interfacial heat transfer, which is evaluated numerically through accounting for both convective and radiative components. A heat transfer ratio, Q I /Q H , is introduced as a dimensionless parameter for interfacial heat transfer, where Q I and Q H are the heat transfer rates at the LB-gas and LB-heated disk interfaces, respectively. It is found that HTWs travel in the same direction as the surface flow for Q I /Q H > 0 (heat-loss condition) while in the opposite direction for Q I /Q H < 0 (heat-gain condition) in the present microgravity experiment. It is shown that the heat-transfer condition alters slightly but appreciably the basic temperature and flow field, the alteration that is not accounted for in the previous linear stability analyses for an infinite LB.