scholarly journals Marangoni convection in binary mixtures with Soret effect

1998 ◽  
Vol 375 ◽  
pp. 143-177 ◽  
Author(s):  
A. BERGEON ◽  
D. HENRY ◽  
H. BENHADID ◽  
L. S. TUCKERMAN
Keyword(s):  
Marangoni Convection ◽  
Soret Effect ◽  
Spectral Element ◽  
Soret Coefficient ◽  
Small Range ◽  
Concentration Gradients ◽  
Time Stepping ◽  
Pure Fluid ◽  
Secondary Bifurcations ◽  
Steady Convection

Marangoni convection in a differentially heated binary mixture is studied numerically by continuation. The fluid is subject to the Soret effect and is contained in a two-dimensional small-aspect-ratio rectangular cavity with one undeformable free surface. Either or both of the temperature and concentration gradients may be destabilizing; all three possibilities are considered. A spectral-element time-stepping code is adapted to calculate bifurcation points and solution branches via Newton's method. Linear thresholds are compared to those obtained for a pure fluid. It is found that for large enough Soret coefficient, convection is initiated predominantly by solutal effects and leads to a single large roll. Computed bifurcation diagrams show a marked transition from a weakly convective Soret regime to a strongly convective Marangoni regime when the threshold for pure fluid thermal convection is passed. The presence of many secondary bifurcations means that the mode of convection at the onset of instability is often observed only over a small range of Marangoni number. In particular, two-roll states with up-flow at the centre succeed one-roll states via a well-defined sequence of bifurcations. When convection is oscillatory at onset, the limit cycle is quickly destroyed by a global (infinite-period) bifurcation leading to subcritical steady convection.

Numerical Analysis of Thermal-Solutal Convection in Heterogeneous Porous Media

2005 ◽  
Vol 73 (1) ◽  
pp. 21-25 ◽  
Author(s):  
Charles-Guobing Jiang ◽  
M. Ziad Saghir ◽  
M. Kawaji
Keyword(s):  
Porous Media ◽  
Thermal Diffusion ◽  
Soret Effect ◽  
Heterogeneous Porous Media ◽  
Soret Coefficient ◽  
Solutal Convection ◽  
Coefficient Distribution ◽  
Separation Ratio ◽  
Diffusion In Porous Media ◽  
Vertical Cavity

Thermal diffusion, or Soret effect, in porous media is mathematically modeled with the Firoozabadi model based on non-equilibrium thermodynamics. The Soret effect in a binary mixture is investigated in a vertical cavity with heterogeneous permeability, where natural convection can occur. The thermo solutal convection with heterogeneous permeability was studied in terms of flow pattern, concentration distribution, component separation ratio, and Soret coefficient distribution. A consistent analysis was conducted and it is concluded that the Soret coefficient of thermal diffusion in porous media strongly depends on the heterogeneity of permeability.

scholarly journals Thermophoresis: The Case of Streptavidin and Biotin

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 376 ◽  
Author(s):  
Doreen Niether ◽  
Mona Sarter ◽  
Bernd W. Koenig ◽  
Jörg Fitter ◽  
Andreas M. Stadler ◽  
...  
Keyword(s):  
Heavy Water ◽  
Rayleigh Scattering ◽  
Soret Effect ◽  
Binding Constants ◽  
Soret Coefficient ◽  
Protein Solutions ◽  
Elastic Neutron ◽  
Solvent Interactions ◽  
Free Protein ◽  
Promising Tool

Thermophoretic behavior of a free protein changes upon ligand binding and gives access to information on the binding constants. The Soret effect has also been proven to be a promising tool to gain information on the hydration layer, as the temperature dependence of the thermodiffusion behavior is sensitive to solute–solvent interactions. In this work, we perform systematic thermophoretic measurements of the protein streptavidin (STV) and of the complex STV with biotin (B) using thermal diffusion forced Rayleigh scattering (TDFRS). Our experiments show that the temperature sensitivity of the Soret coefficient is reduced for the complex compared to the free protein. We discuss our data in comparison with recent quasi-elastic neutron scattering (QENS) measurements. As the QENS measurement has been performed in heavy water, we perform additional measurements in water/heavy water mixtures. Finally, we also elucidate the challenges arising from the quantiative thermophoretic study of complex multicomponent systems such as protein solutions.

The Soret Effect: A Review of Recent Experimental Results

2005 ◽  
Vol 73 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Jean K. Platten
Keyword(s):  
Rayleigh Scattering ◽  
Soret Effect ◽  
Organic Liquid ◽  
Oil Industry ◽  
Liquid Mixtures ◽  
Beam Deflection ◽  
Soret Coefficient ◽  
Onset Of Convection ◽  
New Techniques ◽  
Scattering Technique

In the first part of the paper, we recall what the Soret effect is, together with its applications in science and industry. We emphasize the need to have a reliable data base for the Soret coefficient. Next we review the different techniques to measure the Soret coefficient (elementary Soret cell, beam deflection technique, thermal diffusion forced Rayleigh scattering technique, convective coupling and, in particular, the onset of convection in horizontal layers and the thermogravitational method). Results are provided for several systems, with both negative and positive Soret coefficients, and comparison between several laboratories are made for the same systems. We end with “benchmark” values of the Soret coefficient for some organic liquid mixtures of interest in the oil industry and to which all future new techniques should refer before gaining confidence. We conclude that correct values of the Soret coefficient can be obtained in earth conditions and we deny the need to go to microgravity.

scholarly journals On the Accuracy and Efficiency of Transient Spectral Element Models for Seismic Wave Problems

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Sanna Mönkölä
Keyword(s):  
Fourth Order ◽  
Wave Equations ◽  
Seismic Waves ◽  
Time Discretization ◽  
Spectral Element ◽  
Higher Order ◽  
Time Stepping ◽  
Discretization Schemes ◽  
Elastic Wave Equations ◽  
Wave Problems

This study concentrates on transient multiphysical wave problems for simulating seismic waves. The presented models cover the coupling between elastic wave equations in solid structures and acoustic wave equations in fluids. We focus especially on the accuracy and efficiency of the numerical solution based on higher-order discretizations. The spatial discretization is performed by the spectral element method. For time discretization we compare three different schemes. The efficiency of the higher-order time discretization schemes depends on several factors which we discuss by presenting numerical experiments with the fourth-order Runge-Kutta and the fourth-order Adams-Bashforth time-stepping. We generate a synthetic seismogram and demonstrate its function by a numerical simulation.

Marangoni Asymmetrical Instability in a T-Junction Microchannel With an Open Outlet

2012 ◽  
Author(s):  
Zhenhai Pan ◽  
Hao Wang
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Marangoni Number ◽  
Marangoni Convection ◽  
Main Channel ◽  
The Other ◽  
Side Channel ◽  
Single Vortex ◽  
Steady Convection ◽  
Critical Intensity

The Marangoni convections in microchannels are of interest in various applications such as heat transfer, material and microfluidics. In this paper, the Marangoni asymmetrical instability at a T-junction in a microchannel is investigated. The T-junction is formed by a main channel which water going through and a side channel which is open to the ambient. A convex meniscus is formed in side channel near the T-junction, evaporating/volatizing into the ambient. The consumption of water due to the evaporation is compensated by the supply from the main channel. It is found that for weak evaporations, the evaporation-induced Marangoni convections are symmetrical. However, when the evaporation reaches a critical intensity, the symmetrical Marangoni convection becomes unstable and evolves into an asymmetrical one, with one single vortex under the meniscus. More interestingly, the vortex creates a steady convection through the main channel from its one end to the other, just like a pump. The pumping flow rate is found linearly correlated with the Marangoni number at the T-junction.

scholarly journals Takens–Bogdanov bifurcation of travelling-wave solutions in pipe flow

2011 ◽  
Vol 670 ◽  
pp. 96-129 ◽  
Author(s):  
F. MELLIBOVSKY ◽  
B. ECKHARDT
Keyword(s):  
Relative Equilibria ◽  
Travelling Wave ◽  
Space Structures ◽  
Periodic Flows ◽  
Parabolic Profile ◽  
Time Stepping ◽  
Higher Order Terms ◽  
Modulated Waves ◽  
Secondary Bifurcations ◽  
Unstable Branch

The appearance of travelling-wave-type solutions in pipe Poiseuille flow that are disconnected from the basic parabolic profile is numerically studied in detail. We focus on solutions in the twofold azimuthally-periodic subspace because of their special stability properties, but relate our findings to other solutions as well. Using time-stepping, an adapted Krylov–Newton method and Arnoldi iteration for the computation and stability analysis of relative equilibria, and a robust pseudo-arclength continuation scheme, we unfold a double-zero (Takens–Bogdanov) bifurcating scenario as a function of Reynolds number (Re) and wavenumber (κ). This scenario is extended, by the inclusion of higher-order terms in the normal form, to account for the appearance of supercritical modulated waves emanating from the upper branch of solutions at a degenerate Hopf bifurcation. We provide evidence that these modulated waves undergo a fold-of-cycles and compute some solutions on the unstable branch. These waves are shown to disappear in saddle-loop bifurcations upon collision with lower-branch solutions, in accordance with the bifurcation scenario proposed. The travelling-wave upper-branch solutions are stable within the subspace of twofold periodic flows, and their subsequent secondary bifurcations could contribute to the formation of the phase space structures that are required for turbulent dynamics at higher Re.

Marangoni convection. Part 1. A cavity with differentially heated sidewalls

2000 ◽  
Vol 405 ◽  
pp. 79-110 ◽  
Author(s):  
M. HAMED ◽  
J. M. FLORYAN
Keyword(s):  
Heating Rate ◽  
Marangoni Convection ◽  
Contact Point ◽  
Reynolds Numbers ◽  
Critical Values ◽  
Tangency Condition ◽  
Oscillatory State ◽  
Prandtl Numbers ◽  
Dry Spot ◽  
Steady Convection

Marangoni convection in a cavity with differentially heated sidewalls has been investigated. The analysis includes the complete effects of interface deformation. The results determined for large Biot and zero Marangoni (zero Prandtl) numbers show that steady convection may exist for Reynolds numbers Re larger than, and for capillary numbers Ca and cavity lengths L smaller than, certain critical values. The main factor limiting the existence of steady convection involves the interface becoming tangential to the hot wall at the contact point (tangency condition). Unsteady analysis shows that the tangency condition defines the limit point for the system; its violation is most likely to lead to the formation of a dry spot at the hot wall. The critical values of Re, Ca, and L are mutually dependent and change with the heating rate (they reach a minimum for instantaneous heating). For a certain range of parameters, multiple (i.e. steady and oscillatory) states are possible. The oscillatory state has a form consisting of the steady mode with a simple harmonic sloshing motion superposed on it. A reduction in the heating rate permits heating of the liquid without triggering the oscillatory state. Transition between the steady and the oscillatory states involves a nonlinear instability process.

Experimental Study of Natural Convective Heat and Mass Transfer With Cross Diffusion Effects in Closed Cavity

2009 ◽  
Author(s):  
Wenguang Geng ◽  
Baoming Chen ◽  
Kai Sun ◽  
Li Wang ◽  
Fang Liu
Keyword(s):  
Mass Transfer ◽  
Temperature Gradient ◽  
Heat And Mass Transfer ◽  
Indoor Environment ◽  
Convective Diffusion ◽  
Soret Effect ◽  
Concentration Gradients ◽  
Closed Cavity ◽  
Cross Diffusion ◽  
Diffusion Effects

Natural convective heat and mass transfer with Soret effect and Dufour effect is experimental studied in this paper to investigate the diffusion characteristic of volatile organic compounds (VOCs) in multi-physical fields. Firstly, Soret effect (thermal diffusion effect) experiment is conducted. The transfer process of isobutane and nitrogen in two close container connected by a small-diameter pipe is experimental studied. The results show that temperature difference between the two containers would conduct a solute concentration difference. Furthermore, multi-component convective diffusion experiment in a closed cavity which simulate indoor environment is developed under temperature gradient, humidity and propane gas concentration gradients. In this experiment, Temperature, humidity and concentration of propane could be surveyed real-time and do not interfere the natural convection in the closed cavity. The experiment results show that that the temperature gradient and the water vapor concentration gradient have effects on the convective diffusion of VOCs indoor environment. The cross diffusion effects would be taken into consideration for the problem of simultaneous heat and mass transfer especially in the presence of large temperature and concentration gradients.

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