In order to understand the effect of geometric parameters and axial magnetic field on buoyant-thermocapillary convection during detached solidification, a series of threedimensional numerical simulations were conducte...In order to understand the effect of geometric parameters and axial magnetic field on buoyant-thermocapillary convection during detached solidification, a series of threedimensional numerical simulations were conducted by the finite-difference method. The results indicate that the stable flow is observed when the Marangoni number （Ma） is small; however, when the value of Ma increases and exceeds a threshold value, the stable steady flow transits to be unstable flow. As the height of the melt increases, the flow is enhanced at first and then gets weakened. As the width of gap decreases gradually, the strength of flow is enhanced. The approach of using axial magnetic field is an effective way to suppress the buoyant-thermocapillary convection. As the magnetic field strength increases, the inhibition is enhanced. The critical Marangoni number increases slightly with a greater melt height, a narrower width of gap, and a more strength of magnetic field.展开更多
An experiment is carried out on the surface oscillation of buoyant-thermocapillary convection in an open cylindrical annulus. When the radial temperature difference AT reaches a critical value △Tc, a regular oscillat...An experiment is carried out on the surface oscillation of buoyant-thermocapillary convection in an open cylindrical annulus. When the radial temperature difference AT reaches a critical value △Tc, a regular oscillation appears and soon disappears on the open surface, which varies when the liquid layer＇s thickness h and temperature difference △T are varied. With growth of △T, dominant frequency of the visible oscillation will grow too but is found within certain frequencies. Driving forces, buoyance and thermocapillarity, are responsible for this phenomanon and the ＂balance＂ point is considered to exist when h is between 4.5-5.0 mm. Surface oscillation region is also found restricted within a narrow gap when Bo is smaller than 3.7.展开更多
To cooperate with Chinese TG-2 space experiment project, the transition process from steady to regular oscillatory flow, and finally to chaos is experimentally studied in buoyant-thermocapillary convection. The onset ...To cooperate with Chinese TG-2 space experiment project, the transition process from steady to regular oscillatory flow, and finally to chaos is experimentally studied in buoyant-thermocapillary convection. The onset of oscillation and further transitional convective behavior are detected by measuring the temperature in large-scale liquid bridge of 2eSt silicone oil To identify the various dynamical regimes, the Fourier transform and fractal theory are used to reveal the frequency and amplitude characteristics of the flow motion. The experimental results indicate the co-existence of quasi-periodic and the Feigenbaum bifurcation in chaos.展开更多
基金Project(51076173)supported by the National Natural Science Foundation of China
文摘In order to understand the effect of geometric parameters and axial magnetic field on buoyant-thermocapillary convection during detached solidification, a series of threedimensional numerical simulations were conducted by the finite-difference method. The results indicate that the stable flow is observed when the Marangoni number （Ma） is small; however, when the value of Ma increases and exceeds a threshold value, the stable steady flow transits to be unstable flow. As the height of the melt increases, the flow is enhanced at first and then gets weakened. As the width of gap decreases gradually, the strength of flow is enhanced. The approach of using axial magnetic field is an effective way to suppress the buoyant-thermocapillary convection. As the magnetic field strength increases, the inhibition is enhanced. The critical Marangoni number increases slightly with a greater melt height, a narrower width of gap, and a more strength of magnetic field.
基金supported by the National Natural Science Foundation of China(11032011 and 10972224)Knowledge Innovation Program of Chinese Academy of Sciences(KJCX2-YW-L08)
文摘An experiment is carried out on the surface oscillation of buoyant-thermocapillary convection in an open cylindrical annulus. When the radial temperature difference AT reaches a critical value △Tc, a regular oscillation appears and soon disappears on the open surface, which varies when the liquid layer＇s thickness h and temperature difference △T are varied. With growth of △T, dominant frequency of the visible oscillation will grow too but is found within certain frequencies. Driving forces, buoyance and thermocapillarity, are responsible for this phenomanon and the ＂balance＂ point is considered to exist when h is between 4.5-5.0 mm. Surface oscillation region is also found restricted within a narrow gap when Bo is smaller than 3.7.
基金Supported by the China Manned Space Engineering Program(TG-2)the Strategic Priority Research Program on Space Science of Chinese Academy of Sciences:SJ-10 Recoverable Scientific Experiment Satellite under Grant Nos XDA04020405 and XDA04020202-05the National Natural Science Foundation of China under Grant No11372328
文摘To cooperate with Chinese TG-2 space experiment project, the transition process from steady to regular oscillatory flow, and finally to chaos is experimentally studied in buoyant-thermocapillary convection. The onset of oscillation and further transitional convective behavior are detected by measuring the temperature in large-scale liquid bridge of 2eSt silicone oil To identify the various dynamical regimes, the Fourier transform and fractal theory are used to reveal the frequency and amplitude characteristics of the flow motion. The experimental results indicate the co-existence of quasi-periodic and the Feigenbaum bifurcation in chaos.
