Oscillatory Thermosolutal Capillary Convection of High Prandtl Number Fluid for Liquid Bridge under Gravity Environment

Abstract

An investigation on the oscillating characteristic of temperature and transverse velocity in a half-floating zone liquid bridge for the mixture solution of toluene/n-hexane with the ratio of 0.24/0.76 under gravity has been conducted numerically. In this paper, the free surface is treated as a deformable interface in the direct numerical simulation of liquid bridge by using a mass conserving level set method for the first time. The results show the onset of temperature oscillation is earlier than that of transverse velocity oscillation at the hot corner. The velocity oscillation presents a certain pulsation characteristic compared with the temperature oscillation characteristic. In the transforming process from the stable stage to the oscillatory stage, the coupling effects of the temperature, velocity, free surface and concentration oscillations constitute complete oscillation mechanism of thermosolutal capillary convection. When the concentration difference is ΔC cr =0.1 and temperature difference is ΔT cr =0.5℃, the oscillatory thermosolutal capillary convection is caused by temperature difference, the oscillation form of velocity on the monitoring points near the free surface is a sine curve. In addition, when the temperature difference is ΔT cr =1.0℃, the temperature at hot corner occurs irregular oscillation. At the hot corner, the average oscillating periods of transversal velocity at three monitoring points are T0.04s, and the onset times of transversal velocity is basically the same, t5.53s, which have a lag (t0.01s) compare with onset time of temperature oscillation.