Impact of fluid deformation on mixing-induced chemical reactions in heterogeneous flows

Fast chemical reactions in geophysical flows are controlled by fluid mixing, which perturbs local chemical equilibria and thus triggers chemical reactions. Spatial fluctuations in the flow velocity lead to deformation of material fluid elements, which form the support volumes of transported chemical...

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Detalles Bibliográficos
Autores: Borgne, Tanguy Le, Ginn, Timothy R., Dentz, Marco
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2014
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/140811
Acceso en línea:http://hdl.handle.net/10261/140811
Access Level:acceso abierto
Palabra clave:Flow topology
Fluid deformation
Lamella
Mixing
Porous media
Reactive transport
Descripción
Sumario:Fast chemical reactions in geophysical flows are controlled by fluid mixing, which perturbs local chemical equilibria and thus triggers chemical reactions. Spatial fluctuations in the flow velocity lead to deformation of material fluid elements, which form the support volumes of transported chemical species. We develop an approach based on a lamellar representation of fluid mixing that provides a direct link between fluid deformation, the distribution of concentration gradients, and the upscaled reaction rates for fast reversible reactions. The temporal evolution of effective reaction rates is determined by the flow topology and the distribution of local velocity gradients. This leads to a significant increase of the reaction efficiency, which turns out to be orders of magnitude larger than in homogeneous flow. This approach allows for the systematic evaluation of the temporal evolution of equilibrium reaction rates and establishes a direct link between the reaction efficiency and the spatial characteristics of the underlying flow field as quantified by the deformation of material fluid elements. © 2014. American Geophysical Union. All Rights Reserved.