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Concentration fluctuations in nonisothermal reaction-diffusion systems

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Ortiz de Zárate Leira, José María and Sengers, Jan V. and Bedeaux, Dick and Kjelstrup, Signe (2007) Concentration fluctuations in nonisothermal reaction-diffusion systems. Journal of Chemical Physics, 127 (3). ISSN 0021-9606

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Official URL: http://dx.doi.org/10.1063/1.2746326


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Abstract

In this paper a simple reaction-diffusion system, namely a binary fluid mixture with an association-dissociation reaction between the two components, is considered. Fluctuations at hydrodynamic spatiotemporal scales when a temperature gradient is present in this chemically reacting system are studied. First, fluctuating hydrodynamics when the system is in global equilibrium (isothermal) is reviewed. Comparing the two cases, an enhancement of the intensity of concentration fluctuations in the presence of a temperature gradient is predicted. The nonequilibrium concentration fluctuations are spatially long ranged, with an intensity depending on the wave number q. The intensity exhibits a crossover from a proportional to q(-4) to a proportional to q(-2) behavior depending on whether the corresponding wavelength is smaller or larger than the penetration depth of the reacting mixture. This opens a possibility to distinguish between diffusion- or activation-controlled regimes of the reaction by measuring these fluctuations. In addition, the possible observation of these fluctuations in nonequilibrium molecular dynamics simulations is considered.


Item Type:Article
Additional Information:

© 2007 American Institute of Physics. J.S. and J.O.Z. acknowledge support from The Research Council of Norway, under Grant No 167336/V30 “Transport on a nano-scale; at surfaces and contact lines.” The authors thank Y. Demirel for some useful comments.

Uncontrolled Keywords:Molecular-Dynamics Simulations, Chemical Langevin Equation, Light-Scattering, Nonequilibrium Fluctuations, Temperature-Gradient, Thermal-Equilibrium, Rayleigh-Scattering, Local Equilibrium, Mixture, Fluid
Subjects:Sciences > Physics > Thermodynamics
ID Code:27328
Deposited On:17 Nov 2014 13:48
Last Modified:20 Nov 2014 09:42

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