scholarly journals Defect structures of Rayleigh-Benard travelling wave convection in binary fluid mixtures

2009 ◽  
Vol 58 (4) ◽  
pp. 2528
Author(s):  
Ning Li-Zhong ◽  
Qi Xin ◽  
Yu Li ◽  
Zhou Yang
Keyword(s):  
Travelling Wave ◽  
Defect Structures ◽  
Binary Fluid ◽  
Fluid Mixtures ◽  
Binary Fluid Mixtures ◽  
Rayleigh Benard

scholarly journals Traveling-Wave Convection with Periodic Source Defects in Binary Fluid Mixtures with Strong Soret Effect

Entropy ◽  
2020 ◽  
Vol 22 (3) ◽  
pp. 283
Author(s):  
Laiyun Zheng ◽  
Bingxin Zhao ◽  
Jianqing Yang ◽  
Zhenfu Tian ◽  
Ming Ye
Keyword(s):  
Rayleigh Number ◽  
Traveling Wave ◽  
Soret Effect ◽  
Binary Fluid ◽  
Fluid Mixtures ◽  
Bénard Convection ◽  
Benard Convection ◽  
Binary Fluid Mixtures ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

This paper studied the Rayleigh–Bénard convection in binary fluid mixtures with a strong Soret effect (separation ratio ψ = − 0.6 ) in a rectangular container heated uniformly from below. We used a high-accuracy compact finite difference method to solve the hydrodynamic equations used to describe the Rayleigh–Bénard convection. A stable traveling-wave convective state with periodic source defects (PSD-TW) is obtained and its properties are discussed in detail. Our numerical results show that the novel PSD-TW state is maintained by the Eckhaus instability and the difference between the creation and annihilation frequencies of convective rolls at the left and right boundaries of the container. In the range of Rayleigh number in which the PSD-TW state is stable, the period of defect occurrence increases first and then decreases with increasing Rayleigh number. At the upper bound of this range, the system transitions from PSD-TW state to another type of traveling-wave state with aperiodic and more dislocated defects. Moreover, we consider the problem with the Prandtl number P r ranging from 0.1 to 20 and the Lewis number L e from 0.001 to 1, and discuss the stabilities of the PSD-TW states and present the results as phase diagrams.

The influence of thermal noise on the onset of travelling-wave convection in binary fluid mixtures: an experimental investigation

1994 ◽  
Vol 271 ◽  
pp. 235-265 ◽  
Author(s):  
Wolfgang Schöpf ◽  
Ingo Rehberg
Keyword(s):  
Convective Instability ◽  
Thermal Noise ◽  
Travelling Waves ◽  
Thermal Fluctuations ◽  
Travelling Wave ◽  
Unstable Regime ◽  
Binary Fluid ◽  
Fluid Mixtures ◽  
Wave States ◽  
Binary Fluid Mixtures

When dealing with systems showing a Hopf bifurcation as the first instability from a conductive state leading to travelling waves, the distinction between convective and absolute instability becomes significant. The convectively unstable regime is characterized by the fact that a homogeneous disturbance may have a positive growth rate, while a single localized perturbation cannot trigger the onset of nonlinear convection. In this paper the convective instability occurring in binary fluid mixtures for a negative separation ratio is utilized for amplifying intrinsic thermal fluctuations, which in this way become accessible to quantitative measurements. The experiments are performed in a quasi-one-dimensional convection channel which, by means of subcritical ramps, effectively prevents the reflection of the travelling waves from the sidewalls. Thus, that range of the convective instability within which linear waves can be observed is strongly enhanced. The temperature variations involved in the observed travelling-wave states are quantified by using the shadowgraph method. By resonantly stimulating the system with its linear Hopf frequency, the reflection ability and some coefficients of the amplitude equation appropriate for describing the convection features near onset can be determined. Without stimulation, travelling-wave states of very small amplitudes showing an erratic spatio-temporal behaviour occur spontaneously inside the convectively unstable regime. The temporal correlation function calculated from the measured light intensity caused by these states is compared with a theoretical expression obtained from a Ginzburg—Landau equation containing a noise term. A very good agreement is found for the amplitude if thermal noise is assumed to be the reason for these fluctuating convection rolls, thus supporting the idea that the response of the system to thermal fluctuations is observed.

scholarly journals Stability boundaries of roll and square convection in binary fluid mixtures with positive separation ratio

2000 ◽  
Vol 408 ◽  
pp. 121-147 ◽  
Author(s):  
B. HUKE ◽  
M. LÜCKE ◽  
P. BÜCHEL ◽  
CH. JUNG
Keyword(s):  
Three Dimensional ◽  
Stationary Solutions ◽  
Stability Boundaries ◽  
Binary Fluid ◽  
Fluid Mixtures ◽  
Separation Ratio ◽  
Wide Range ◽  
The Stability ◽  
Binary Fluid Mixtures ◽  
Rayleigh Benard

Rayleigh–Bénard convection in horizontal layers of binary fluid mixtures heated from below with realistic horizontal boundary conditions is studied theoretically using multi-mode Galerkin expansions. For positive separation ratios the main difference between the mixtures and pure fluids lies in the existence of stable three-dimensional patterns near onset in a wide range of the parameter space. We evaluated the stationary solutions of roll, crossroll, and square convection and we determined the location of the stability boundaries for many parameter combinations thereby obtaining the Busse balloon for roll and square patterns.

Fully developed traveling-wave convection in binary fluid mixtures

1989 ◽  
Vol 63 (4) ◽  
pp. 376-379 ◽  
Author(s):  
W. Barten ◽  
M. Lücke ◽  
W. Hort ◽  
M. Kamps
Keyword(s):  
Traveling Wave ◽  
Binary Fluid ◽  
Fluid Mixtures ◽  
Binary Fluid Mixtures

Pattern study of thermal phase separation for binary fluid mixtures

2011 ◽  
Vol 21 (5) ◽  
pp. 572-583 ◽  
Author(s):  
Adriano Tiribocchi ◽  
Antonio Piscitelli ◽  
Giuseppe Gonnella ◽  
Antonio Lamura
Keyword(s):  
Phase Separation ◽  
Binary Fluid ◽  
Fluid Mixtures ◽  
Thermal Phase ◽  
Binary Fluid Mixtures

scholarly journals Collisions of localized convection structures in binary fluid mixtures

2012 ◽  
Vol 14 (9) ◽  
pp. 093055 ◽  
Author(s):  
A V Taraut ◽  
B L Smorodin ◽  
M Lücke
Keyword(s):  
Binary Fluid ◽  
Fluid Mixtures ◽  
Binary Fluid Mixtures
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