Flow pattern transition and destabilization mechanism of thermocapillary convection for low Prandtl number fluid in a deep annular pool with surface heat dissipation

Abstract

In order to understand clearly the flow pattern transition and the destabilization mechanism of thermocapillary convection for low Prandtl number fluids in a deep annular pool with surface heat dissipation, we carried out a series of three-dimensional numerical simulations by using the finite volume method. The radius ratio and the aspect ratio of an annular pool are respectively fixed at 0.5 and 1.0. Prandtl number of the working fluid is 0.011. Because the total heat dissipation coefficient on the free surface for low Prandtl fluids is small, Biot number is varied from 0 to 1.0. Results indicate that thermocapillary convection experiences the transitions from axisymmetric steady state flow into three-dimensional steady flow, and then into three-dimensional oscillation flow with the increase of Marangoni number. The critical Marangoni number of flow pattern transition decreases slightly with the increase of Biot number, and the maximum temperature and velocity fluctuations appear near the lower part of outer wall. The azimuthal temperature fluctuation on the free surface gradually shrinks to the inner wall, and the temperature fluctuation region decreases. However, it remains almost unchanged near the bottom of the annular pool, but the fluctuation amplitude increases.

Photostimulated Spiropyran for Instantaneous Visualization of Thermal Field Distribution and Flow Pattern

“…Especially, the dynamic behaviors of flows driven by a horizontal temperature gradient in fluid layers with a free upper surface have attracted the attention of the researchers for many years . Many experiments have been designed and carried out in liquid pools with various geometries to investigate the relationships between the dynamic behaviors of flows and environmental parameters. − Over the course of these experiments, some measurement methods and tools are developed to obtain information on the state of flows. For instance, infrared cameras, thermo-chromic liquid crystals, and phosphorescence-based visualization techniques are common optical tools used for two-dimensional temperature measurement; the conjunction technology of particle image velocimetry and polystyrene fluorescent particles are employed to trace the patterns of the thermocapillary flows .…”

Visualization of temperature distribution and flow behavior in water evaporation using water‐soluble spiropyran

“…Column chromatography was performed on silica gel 60 (200-300 mesh ASTM). 1 H NMR and 13 C NMR spectra were collected using Bruker spectroscopy (Ascend 400, MHz). Electrospray ionization mass spectra (ESI-MS) were obtained using an Agilent Model 1260 HPLC-6500Q-TOF mass spectrometer.…”

“…To this end, numerous experiments have been conducted in liquid containers with various geometries to study the correlation between dynamic flow behaviors and environmental factors. [13][14][15][16][17][18] Throughout these experiments, specific measurement methods and tools have been developed to gather information about thermal field distribution.…”

Numerical Simulation of Thermocapillary Convection in a Half-Zone Liquid Bridge Model with Large Aspect Ratio under Microgravity

“…Figure 12 is the temperature STD diagram of the liquid bridge in the standing wave state on the z = 0 plane. The temperature STD image is in the shape of a wave, which indicates that the thermocapillary wave is a standing wave (Zhang et al, [26]). The thermocapillary wave number is also 1.…”