scholarly journals A new cognition on oscillatory thermocapillary convection for high Prandtl number fluids

2020 ◽  
pp. 234-234
Author(s):  
Shuo Yang ◽  
Guofeng Wang ◽  
Shanshan Ma ◽  
Yu Gao
Keyword(s):  
Free Surface ◽  
Liquid Bridge ◽  
Normal Gravity ◽  
Thermocapillary Convection ◽  
Temperature Oscillation ◽  
Surface Flow ◽  
Oscillatory Mechanism ◽  
High Prandtl Number ◽  
Transfer Direction ◽  
First Time

A direct numerical simulations on the oscillatory thermocapillary convection in a non-axisymmetric liquid bridge of high Pr fluids under normal gravity has been conducted by using a new method of mass conserving Level Set method for capturing any micro-scale migrations of free surface. Against the former studies, the oscillatory behaviors of surface flow (the perturbation of velocity, temperature, and free surface) and flow pattern have been quantitatively investigated simultaneously for the first time. The present results show that the instability of thermocapillary convection originates from the oscillations of velocity, temperature, and free surface at the hot corner. The velocity oscillation responds slowly to the temperature oscillation, which are opposite in transfer direction for each other, resulting in the free surface oscillation. The oscillatory thermocapillary convection in the liquid bridge is eventually excited by the coupling effects of these three kinds of oscillations, which discloses clearly the oscillatory mechanism of thermocapillary convection for high Pr fluids.

scholarly journals The effect of uniform magnetic field on spatial-temporal evolution of thermocapillary convection with the silicon oil based ferrofluid

2020 ◽  
Vol 24 (6 Part B) ◽  
pp. 4159-4171
Author(s):  
Shuo Yang ◽  
Rui Ma ◽  
Qiaosheng Deng ◽  
Guofeng Wang ◽  
Yu Gao ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Free Surface ◽  
Transverse Magnetic Field ◽  
Liquid Bridge ◽  
Thermocapillary Convection ◽  
Surface Deformation ◽  
Axial Magnetic Field ◽  
Transverse Magnetic ◽  
Surface Flow ◽  
Silicon Oil

A uniform axial or transverse magnetic field is applied on the silicon oil based ferrofluid of high Prandtl number fluid (Pr ? 111.67), and the effect of magnetic field on the thermocapillary convection is investigated. It is shown that the location of vortex core of thermocapillary convection is mainly near the free surface of liquid bridge due to the inhibition of the axial magnetic field. A velocity stagnation region is formed inside the liquid bridge under the axial magnetic field (B = 0.3-0.5 T). The disturbance of bulk reflux and surface flow is suppressed by the increasing axial magnetic field. There is a dynamic response of free surface deformation to the axial magnetic field, and then the contact angle variation of the free surface at the hot corner is as following, ?hot, B = 0.5 T = 83.34? > ?hot, B = 0.3 T = 72.16? > > ?hot,B = 0.1 T = 54.21? > ?hot, B = 0 T = 43.33?. The results show that temperature distribution near the free surface is less and less affected by thermocapillary convection with the increasing magnetic field, and it presents a characteristic of heat-conduction. In addition, the transverse magnetic field does not realize the fundamental inhibition for thermocapillary convection, but it transfers the influence of thermocapillary convection to the free surface.

Influence of Ambient Airflow on Free Surface Deformation and Flow Pattern Inside Liquid Bridge With Large Prandtl Number Fluid (Pr > 100) Under Gravity

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Shuo Yang ◽  
Ruquan Liang ◽  
Song Xiao ◽  
Jicheng He ◽  
Shuo Zhang
Keyword(s):  
Free Surface ◽  
Prandtl Number ◽  
Liquid Bridge ◽  
Thermocapillary Convection ◽  
Surface Deformation ◽  
Flow Cell ◽  
Thermocapillary Force ◽  
Flow Cells ◽  
Lower Disk ◽  
Free Surface Deformation

The influence of airflow shear on the free surface deformation and the flow structure for large Prandtl number fluid (Pr = 111.67) has been analyzed numerically as the parallel airflow shear is induced into the surrounding of liquid bridge from the lower disk or the upper disk. Contrasted with former studies, an improved level set method is adopted to track any tiny deformation of free surface, where the area compensation is carried out to compensate the nonconservation of mass. Present results indicate that the airflow shear can excite flow cells in the isothermal liquid bridge. The airflow shear induced from the upper disk impulses the convex region of free interface as the airflow shear intensity is increased, which may exceed the breaking limit of liquid bridge. The free surface is transformed from the “S”-shape into the “M”-shape as the airflow shear is induced from the lower disk. For the nonisothermal liquid bridge, the flow cell is dominated by the thermocapillary convection at the hot corner if the airflow shear comes from the hot disk, and another reversed flow cell near the cold disk appears. While the shape of free surface depends on the competition between the thermocapillary force and the shear force when the airflow is induced from the cold disk.

scholarly journals The Payload Development and the Experiments for Studying Thermocapillary Convection in TG-2 Liquid Bridge

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Li Duan ◽  
Qi Kang ◽  
Jianquan Zhang ◽  
Xiang Li ◽  
Liang Hu ◽  
...  
Keyword(s):  
Liquid Bridge ◽  
Thermocapillary Convection ◽  
Silicone Oil ◽  
Volume Ratio ◽  
High Sensitivity ◽  
Temperature Oscillation ◽  
Space Experiment ◽  
Fluid Temperature ◽  
Fluid Medium ◽  
Space Experiments

AbstractThe development of space experiment payload for studying thermocapillary convection in the liquid bridge with large Pr number on TG-2 space laboratory as well as the experiments are presented in detail in this paper, and the objectives of the space experiments are confirmed. The functions of the payload are analyzed, and the technical and engineering specifications are determined. Detailed designs and experimental verifications are performed on the structure of liquid bridge columns, the method of bubble removing in the liquid, the bridge cleaning system, the accurate control of aspect ratio and volume ratio, and the high-sensitivity measurement of fluid temperature. Matching experiments on the ground according to space experiment properties are carried out, 5cSt silicone oil is selected as the fluid medium in space experiments. And the states of liquid bridge and temperature oscillation signals obtained from space experiments are presented at the end of this paper. Specific summarizations and discussions to the experiment project on fluid science in space are conducted in this paper, which will provide a useful reference for scientists participating space experimental research in the future.

COMPUTATION OF THE FREE SURFACE FLOW OF A THIN LIQUID FILM AT ZERO AND NORMAL GRAVITY

1990 ◽  
Vol 17 (1) ◽  
pp. 53-71 ◽  
Author(s):  
M. M. Rahman ◽  
A. Faghri ◽  
W. L. Hankey ◽  
T. D. Swanson
Keyword(s):  
Free Surface ◽  
Liquid Film ◽  
Normal Gravity ◽  
Thin Liquid Film ◽  
Free Surface Flow ◽  
Surface Flow
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