Depth Dependence of the Big Wave in Belousov-Zhabotinsky Reaction

Inomoto, Osamu; Ariyoshi, Takayuki; Inanaga, Seiji; Kai, Shoichi

doi:10.1143/jpsj.64.3602

Cited by 12 publications

(6 citation statements)

References 10 publications

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“…Indeed, the depth dependence of the dynamics has received much interest in various chemical systems. 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%

“…21 An accelerating chemical wave, also called big wave, accompanied by large hydrodynamic motions and surface deformation propagation has also been experimentally well characterized. [22][23][24][25][26] Transduction of these chemically driven flows into spontaneous motion of an aqueous droplet of BZ reaction medium on an oil phase has even been evidenced. 27,28 Since the BZ reaction is an exothermic reaction involving surface-active compounds, 29,30 inhomogeneities in surface tension or in density are supposed to play a key role in these fluid motions even though detailed understanding of the underlying mechanisms and of their parametric dependence is still lacking.…”

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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“…These changes can trigger natural convection, which has long been experimentally evidenced to, in turn, deform autocatalytic fronts and accelerate their propagation. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In vertically-oriented closed systems where the reactor is entirely filled with the reacting solution and the front travels parallel to the gravity field, convective flows can be induced by density differences only. The resulting density fingering of the front has been well characterized both experimentally and theoretically.…”

Section: Introductionmentioning

confidence: 99%

Convective dynamics of traveling autocatalytic fronts in a modulated gravity field

Horváth

Budroni

Bába

et al. 2014

Phys. Chem. Chem. Phys.

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When traveling in thin solution layers, autocatalytic chemical fronts may be deformed and accelerated by convective currents that develop because of density and surface tension gradients related to concentration and thermal gradients across the front. On earth, both buoyancy and Marangoni related flows can act in solution layers open to the air while only buoyancy effects operate in covered liquid layers. The respective effects of density and surface tension induced convective motions are analysed here by studying experimentally the propagation of autocatalytic fronts in uncovered and covered liquid layers during parabolic flights in which the gravity field is modulated periodically. We find that the velocity and deformation of the front are increased during hyper-gravity phases and reduced in the micro-gravity phase. The experimental results compare well with numerical simulations of the evolution of the concentration of the autocatalytic product coupled to the flow field dynamics described by Navier-Stokes equations.

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“…Actually, chemical fronts of well-known reactions such as the Belousov-Zhabotinskii ͑BZ͒ reaction or the iodate-arsenous acid reaction have long been noted to propagate with nonconstant velocities in horizontal thin layers of liquid in contact with air. [5][6][7][8][9][10][11][12] Such reactions involve variations of the solution density and surface tension, which suggests that convection resulting from a combination between buoyancy and Marangoni effects may affect the dynamics of these systems. [13][14][15][16] By using simple models where only one type of convective flow is present, theoretical and numerical approaches are essential in differentiating between the various effects coming into play and in obtaining better understanding of the complex dynamics of such coupled systems.…”

Section: Introductionmentioning

confidence: 99%

Asymptotic structure of steady nonlinear reaction-diffusion-Marangoni convection fronts

2008

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Chemical fronts propagating in horizontal liquid layers with a free surface can induce localized steady Marangoni flow. Numerical integration of the Stokes equations coupled to a reaction-diffusion-convection equation for the concentration of the surface-active reaction product shows that the system reaches an asymptotic dynamic state characterized by a deformed front surrounded by a steady convection roll traveling at a constant speed. To understand the basic balances determining this steady dynamics, we present here an asymptotic analysis of the system based on the numerically obtained scalings at high Marangoni numbers M quantifying the interaction between reaction-diffusion processes and Marangoni convection. M is positive ͑negative͒ when the product decreases ͑increases͒ the surface tension behind the front. We obtain a semianalytical solution for the product concentration for large M Ͼ 0, showing that the key balances are between reaction, convection, and vertical ͑rather than axial͒ diffusion. For M Ͻ 0, we present evidence of a multiscale structure of the front resulting from more complex balances.

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Depth Dependence of the Big Wave in Belousov-Zhabotinsky Reaction

Cited by 12 publications

References 10 publications

Steady Marangoni flow traveling with chemical fronts

Steady Marangoni flow traveling with chemical fronts

Convective dynamics of traveling autocatalytic fronts in a modulated gravity field

Asymptotic structure of steady nonlinear reaction-diffusion-Marangoni convection fronts

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