Numerical study on the effects of convective and radiative heat transfer on thermocapillary convection in a high-Prandtl-number liquid bridge in weightlessness

Abstract

This paper reports the effects of interfacial heat transfer due to convection and radiation on thermocapillary convection in a liquid bridge of high-Prandtl-number fluids (i.e., Pr = 67) in weightlessness. A liquid bridge is placed inside a cylindrical chamber filled with argon gas, and the two-dimensional (i.e., axisymmetric) time-independent flow and temperature fields in the liquid bridge and in the ambient gas are numerically simulated. The effect of interfacial heat transfer is investigated by providing forced ambient gas flow and by changing the temperature of the chamber wall. It is confirmed that convective heat transfer is more sensitive to the ambient gas motion than to the chamber wall temperature, whereas radiative heat transfer shows the opposite tendency. The primary component of the heat transfer on the liquid bridge free surface is determined to be convection for many cases. However, when the directions of gas flow and thermocapillary flow coincide, the radiative component can exceed the convective component even under conditions with strong ambient gas flow. The interfacial heat transfer strongly affects the flow and temperature fields of thermocapillary convection in a liquid bridge not only in the vicinity of the free surface but also in the interior region. The present study is expected to contribute to the upcoming microgravity experiment called JEREMI, which focuses on the effect of interfacial heat transfer on thermocapillary convection in a high-Pr liquid bridge.