Hydrodynamic instabilities and photochemical reactions

Micheau, J. C.; Giménez, M.; Borckmans, Pierre; Dewel, Guy

doi:10.1038/305043a0

Cited by 71 publications

(23 citation statements)

References 13 publications

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“…7,8,15,16,[24][25][26] Next, different effects may be progressively added to the model, such as the thermal effects linked to the enthalpy of the reaction 8,16 or to evaporative cooling arising in uncovered layers. 9 …”

Section: Discussionmentioning

confidence: 99%

“…8 The role of hydrodynamics in the evolution of chemical systems driven far from equilibrium has long been emphasized in the case of spatial structures generated at diverse interfaces. [9][10][11][12][13] In the case of chemical front systems, the spatiotemporal distribution of heat and mass resulting from the front propagation can affect the density, the viscosity, and the surface tension of the reaction solution, thereby eventually initiating convection.…”

Section: Introductionmentioning

confidence: 99%

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Steady Marangoni flow traveling with chemical fronts

Rongy

Wit

2006

The Journal of Chemical Physics

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When autocatalytic chemical fronts propagate in thin layers of solution in contact with air, they can induce capillary flows due to surface tension gradients across the front ͑Marangoni flows͒. We investigate here such an interplay between autocatalytic reactions, diffusion, and Marangoni effects with a theoretical model coupling the incompressible Navier-Stokes equations to a conservation equation for the autocatalytic product concentration in the absence of gravity and for isothermal conditions. The boundary condition at the open liquid/air interface takes the surface activity of this product into account and introduces the solutal Marangoni number M representing the intensity of the coupling between hydrodynamics and reaction-diffusion processes. Positive and negative Marangoni numbers correspond, respectively, to the cases where the product decreases or increases surface tension behind the front. We show that, in both cases, such coupled systems reach an asymptotic dynamics characterized by a steady fluid vortex traveling at a constant speed with the front and deforming it, with, however, an asymmetry between the results for positive and negative M. A parametric study shows that increased propagation speed, front deformation, and possible transient oscillating dynamics occur when the absolute value of M is increased.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Steady Marangoni flow traveling with chemical fronts

Rongy

Wit

2006

The Journal of Chemical Physics

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“…Under the action of gravity the denser liquid sinks into the less dense one inducing a convective pattern which progresses in time. Such chemically driven buoyancy-related patterns have received increasing attention during the last years both from experimental (Sherwood and Wei, 1957;Micheau et al, 1983;Kagan, 1984, 1995;Pons et al, 2000;Ermakov et al, 2001;Karlov et al, 2002) and theoretical (Citri et al, 1990;Pé rezVillar et al, 2000;Bees et al, 2001) point of view. Recently, convective phenomena related to such buoyancy effects due to an exothermic A þB-C neutralization reaction close to an immiscible liquid-liquid interface have been studied experimentally by Eckert and Grahn (1999), Eckert et al (2004), Bratsun et al (2005), Shi et al (2005), Eckert (2006, 2007).…”

Section: Introductionmentioning

confidence: 99%

Buoyancy-driven pattern formation in reactive immiscible two-layer systems

Bratsun

Wit

2011

Chemical Engineering Science

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a b s t r a c tBuoyancy-driven convection can be induced by concentration and temperature gradients near the interface between two immiscible fluids filling a vertical Hele-Shaw cell, each of them containing a reactant of an exothermic A þ B-C reaction taking place in the bulk of the lower layer. A chemohydrodynamical pattern appears then due to the combined action of Rayleigh-Taylor, diffusive layer convection and Rayleigh-Bé nard instabilities occurring either below or above the interface. The mathematical model we develop to describe such dynamics consists in a set of reaction-diffusionadvection equations ruling the evolution of concentrations and temperature coupled to Navier-Stokes equation, written in a Hele-Shaw approximation. We perform numerical simulations of the non-linear system and study the influence on pattern formation of changes in the Damköhler number of the problem and in the ratio of initial reactant concentrations.

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“…The reaction-diffusion theory of pattern formation was first proposed by Turing (1) and has been extensively elaborated (2,3). Spatiotemporal breaking of symmetry has been observed with a number of chemical (4)(5)(6) and photochemical (7,8) reactions. Interest in obtaining stationary spatial dissipative structures has been renewed (9)(10)(11)(12)(13)(14).…”

mentioning

confidence: 99%

“…The reaction-diffusion theory of pattern formation was first proposed by Turing (1) and has been extensively elaborated (2, 3). Spatiotemporal breaking of symmetry has been observed with a number of chemical (4-6) and photochemical (7,8) MATERIALS AND METHODS Preparation of Thylakoids. Chloroplast thylakoids (22,23) were isolated from lettuce (Lactuca sativa var.…”

Section: Introductionmentioning

confidence: 99%

Spatial patterns in a photobiochemical system

Aon

Thomas²,

Hervagault³

1989

Proc. Natl. Acad. Sci. U.S.A.

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Illumination of a system consisting of a vertical tube containing an unstirred homogeneous suspension of thylakoids in an imposed linear concentration gradient of an electron acceptor, 2,6-dichloroindophenol, gave rise to a onedimensional banded pattern of the acceptor that evolved in a time-dependent manner. The spatial pattern was obtained only within certain parameters of the dichloroindophenol gradient and with certain concentrations of thylakoids. Various numbers of bands were obtained by varying the gradient parameters, the thylakoid concentration, or both. Pattern formation was reaction-dependent since inhibition of the water-splitting system, either by a physical (heating) or by a chemical (methylamine) method, resulted in abolition of the spatial periodicity. Obtaining the self-organized redox transition of dichloroindophenol in a gelled medium suggests that pattern formation in this system could be explained mainly by a reaction-diffusion mechanism.It has been shown from both theoretical and experimental points of view that many chemical, biological, and biochemical processes exhibit well defined spatiotemporal patterns. Pattern formation has been explained by models based on reaction-diffusion mechanisms. The reaction-diffusion theory of pattern formation was first proposed by Turing (1) and has been extensively elaborated (2, 3). Spatiotemporal breaking of symmetry has been observed with a number of chemical (4-6) and photochemical (7,8) MATERIALS AND METHODS Preparation of Thylakoids. Chloroplast thylakoids (22,23) were isolated from lettuce (Lactuca sativa var. romaine) as described by Dilley (24) with only slight modifications: the grinding solution contained 0.4 M sucrose, 20 mM HepesNaOH (pH 8.2), and 10 mM NaCI. The final pellet was resuspended in a medium consisting of 0.1 M sucrose, 10 mM Hepes-NaOH (pH 8.2), and 10 mM NaCl. Experiments were performed with fresh thylakoid preparations corresponding to an activity of 5 ,umol of 2,6-dichloroindophenol (DCIP) reduced per mg of chlorophyll per hr/ml.Experimental Production of One-Dimensional Patterns. Thylakoids corresponding to 0.57 mg of chlorophyll were suspended in a solution containing 50 mM Hepes-NaOH (pH 8.2), 0.2 M sucrose, 50 mM NaCl, and 0.83 mM MgCl2 (thylakoid suspension) and a linear gradient of DCIP was imposed as described below. Heterogeneity in the distribution of thylakoids, due to gravity, is unlikely: by using Stoke's law, we calculated (5-min induction time) that a thylakoid membrane will fall at a rate of 50 nm/sec-that is, <1% of a band thickness (2 mm).The linear gradient of the electron acceptor was formed in 15 min by mixing two thylakoid suspensions containing different concentrations of DCIP, with the use of an LKB model 11300 Ultrograd gradient mixer. Gradients are characterized by two parameters: parameter a, the concentration difference of DCIP (as mM) between the top and the bottom of the test tube, and parameter b, the lower concentration value of DCIP (as mM). A test tube (1.2 cm in diameter) was filled ...

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Hydrodynamic instabilities and photochemical reactions

Cited by 71 publications

References 13 publications

Steady Marangoni flow traveling with chemical fronts

Steady Marangoni flow traveling with chemical fronts

Buoyancy-driven pattern formation in reactive immiscible two-layer systems

Spatial patterns in a photobiochemical system

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