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| Titel |
A Transition in the Cumulative Reaction Rate of Two Species Diffusion with Bimolecular Reaction |
| VerfasserIn |
Harihar Rajaram, Masoud Arshadi |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108490
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| Publikation (Nr.) |
 EGU/EGU2015-8245.pdf |
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| Zusammenfassung |
| Diffusion and bimolecular reaction between two initially separated reacting species is a
prototypical small-scale description of reaction induced by transverse mixing. It is also
relevant to diffusion controlled transport regimes as encountered in low-permeability matrix
blocks in fractured media. In previous work, the reaction-diffusion problem has
been analyzed as a Stefan problem involving a distinct moving boundary (reaction
front), which predicts that front motion scales as /t, and the cumulative reaction
rate scales as 1//t-. We present a general non-dimensionalization of the problem
and a perturbation analysis to show that there is an early time regime where the
cumulative reaction rate scales as /t- rather than 1//t. The duration of this early time
regime (where the cumulative rate is kinetically rather than diffusion controlled)
depends on the rate parameter, in a manner that is consistently predicted by our
non-dimensionalization. We also present results on the scaling of the reaction front
width. We present numerical simulations in homogeneous and heterogeneous porous
media to demonstrate the limited influence of heterogeneity on the behavior of the
reaction-diffusion system. We illustrate applications to the practical problem of in-situ
chemical oxidation of TCE and PCE by permanganate, which is employed to remediate
contaminated sites where the DNAPLs are largely dissolved in the rock matrix. |
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