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| Titel |
Application of block-scale effective dispersion to reactive transport simulations in groundwater |
| VerfasserIn |
Paulo Herrera, Joaquin Cortinez, Albert Valocchi |
| 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 |
250107426
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| Publikation (Nr.) |
 EGU/EGU2015-7127.pdf |
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| Zusammenfassung |
| In the groundwater literature, macrodispersion has traditionally been derived and applied to account for plume spreading –i.e. deformation of the water volume that contains solute mass- due to the overall heterogeneity of aquifers. Several experimental and numerical studies have verified that the use of a macrodispersion coefficient within an advection-dispersion equation can reproduce plume spreading in mildly heterogeneous aquifers. More recently, there have been new extensions to the macrodispersion theory to separately account for block-scale filtering effects due to the use of finite-size numerical grids, and for deriving effective macrodispersion coefficients to account for solute mixing and dilution.
We combine the concepts of block-scale dependent and effective dispersion to account for the effect of unresolved subgrid-scale heterogeneity on synthetic numerical simulations of a mixing controlled bimolecular reaction. We demonstrate that by using a time-dependent effective block-scale dispersion coefficient we are able to reproduce overall reaction rates for different scenarios defined according to parameters such as: grid size, Peclet number, aquifer heterogeneity, etc. Moreover, we verify that for long-times the block-scale effective dispersion coefficient that reproduces mixing is equal to the previously derived block-scale dispersion coefficient that reproduces spreading. Given that the block-scale dispersion coefficient is similar to the traditional macrodispersion coefficient in the limit of infinitely large block-sizes, we conclude that the block-scale time-dependent dispersion coefficient constitutes a natural extension of the macrodispersion theory that provides a unified framework for numerical simulations of reactive transport in heterogeneous aquifers. |
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