Reactive mixing in heterogeneous porous media flows: concentration gradient distribution, spatial intermittency and temporal scaling of effective reaction kinetics - Archive ouverte HAL Access content directly
Conference Papers Year :

Reactive mixing in heterogeneous porous media flows: concentration gradient distribution, spatial intermittency and temporal scaling of effective reaction kinetics

(1) , (2) , (3) , (4)
1
2
3
4

Abstract

Reactive mixing processes play a central role in a range of porous media systems, including CO2 sequestration operations, reactive geothermal dipoles, biofilms, or flow-through reactors. Many of these reactions are limited by fluid mixing processes that bring the reactants into contact. Hence, the temporal dynamics of effective global reactivity is determined by the creation of concentration gradients by fluid stretching and their dissipation by diffusion [1,2]. From the analysis of the elongation and aggregation of lamellar structures formed in the transported scalar fields, we derive analytical predictions for the probability density functions of concentration gradients in heterogeneous Darcy flows over a large range of Péclet numbers and permeability field variances. In this framework, we show that heterogeneous Darcy fields generate highly intermittent concentration fields, as manifested by the spatial scaling of structure functions. The resulting effective reaction rates display a range of temporal behaviors that depend on the degree of heterogeneity. In the large Damköhler limit, we derive analytical expressions for these temporal scalings in the different regimes that arise when exploring the Péclet number space. We generalize these results for different random flows, including turbulent flows. References: [1] Le Borgne, T., M. Dentz, E. Villermaux, The lamellar description of mixing in porous media, J. of Fluid Mech., vol. 770, pp. 458-498 [2] Le Borgne, T., M. Dentz, E. Villermaux, Stretching, coalescence and mixing in porous media, Phys. Rev. Lett., 110, 204501 (2013)
Not file

Dates and versions

insu-01241980 , version 1 (11-12-2015)

Identifiers

  • HAL Id : insu-01241980 , version 1

Cite

Tanguy Le Borgne, Marco Dentz, Timothy Ginn, Emmanuel Villermaux. Reactive mixing in heterogeneous porous media flows: concentration gradient distribution, spatial intermittency and temporal scaling of effective reaction kinetics. AGU Fall Meeting 2015, American Geophysical Union, Dec 2015, San Francisco, United States. pp.H24A-02. ⟨insu-01241980⟩
162 View
0 Download

Share

Gmail Facebook Twitter LinkedIn More