Publication Details |
| Category | Text Publication |
| Reference Category | Journals |
| DOI | 10.1029/2001WR001203 |
| Title (Primary) | Macrodispersivity for transport in arbitrary nonuniform flow fields: asymptotic and preasymptotic results |
| Author | Lunati, I.; Attinger, S.; Kinzelbach, W. |
| Source Titel | Water Resources Research |
| Year | 2002 |
| Department | CHS |
| Volume | 38 |
| Issue | 10 |
| Page From | 1187 |
| Language | englisch |
| Keywords | homogenization theory; two-scale analysis; nonuniform flow; upscaling; macrodispersivity |
| Abstract | We use homogenization theory to investigate the asymptotic macrodispersion in arbitrary nonuniform velocity fields, which show small-scale fluctuations. In the first part of the paper, a multiple-scale expansion analysis is performed to study transport phenomena in the asymptotic limit ? « 1, where ? represents the ratio between typical lengths of the small and large scale. In this limit the effects of small-scale velocity fluctuations on the transport behavior are described by a macrodispersive term, and our analysis provides an additional local equation that allows calculating the macrodispersive tensor. For Darcian flow fields we show that the macrodispersivity is a fourth-rank tensor. If dispersion/diffusion can be neglected, it depends only on the direction of the mean flow with respect to the principal axes of anisotropy of the medium. Hence the macrodispersivity represents a medium property. In the second part of the paper, we heuristically extend the theory to finite ? effects. Our results differ from those obtained in the common probabilistic approach employing ensemble averages. This demonstrates that standard ensemble averaging does not consistently account for finite scale effects: it tends to overestimate the dispersion coefficient in the single realization. |
| Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=5770 |
| Lunati, I., Attinger, S., Kinzelbach, W. (2002): Macrodispersivity for transport in arbitrary nonuniform flow fields: asymptotic and preasymptotic results Water Resour. Res. 38 (10), 1187 10.1029/2001WR001203 |
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