Lagrangian scheme to model subgrid-scale mixing and spreading in heterogeneous porous media
Author
dc.contributor.author
Herrera, P. A.
Author
dc.contributor.author
Cortinez, J. M.
Author
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Valocchi, A. J.
Admission date
dc.date.accessioned
2018-05-16T21:17:40Z
Available date
dc.date.available
2018-05-16T21:17:40Z
Publication date
dc.date.issued
2017
Cita de ítem
dc.identifier.citation
Water Resour. Res., 53, 3302–3318
es_ES
Identifier
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10.1002/2016WR019994
Identifier
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https://repositorio.uchile.cl/handle/2250/147826
Abstract
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Small-scale heterogeneity of permeability controls spreading, dilution, and mixing of solute
plumes at large scale. However, conventional numerical simulations of solute transport are unable to resolve
scales of heterogeneity below the grid scale. We propose a Lagrangian numerical approach to implement
closure models to account for subgrid-scale spreading and mixing in Darcy-scale numerical simulations of
solute transport in mildly heterogeneous porous media. The novelty of the proposed approach is that it
considers two different dispersion coefficients to account for advective spreading mechanisms and localscale
dispersion. Using results of benchmark numerical simulations, we demonstrate that the proposed
approach is able to model subgrid-scale spreading and mixing provided there is a correct choice of blockscale
dispersion coefficient. We also demonstrate that for short travel times it is only possible to account for
spreading or mixing using a single block-scale dispersion coefficient. Moreover, we show that it is necessary
to use time-dependent dispersion coefficients to obtain correct mixing rates. On the contrary, for travel
times that are large in comparison to the typical dispersive time scale, it is possible to use a single expression
to compute the block-dispersion coefficient, which is equal to the asymptotic limit of the block-scale
macrodispersion coefficient proposed by Rubin et al. (1999). Our approach provides a flexible and efficient
way to model subgrid-scale mixing in numerical models of large-scale solute transport in heterogeneous
aquifers. We expect that these findings will help to better understand the applicability of the advectiondispersion-
equation (ADE) to simulate solute transport at the Darcy scale in heterogeneous porous media.
es_ES
Patrocinador
dc.description.sponsorship
Conicyt Chile through project Fondecyt, 11110228 / Fondap Project, 15090013