Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4526669 | Advances in Water Resources | 2007 | 17 Pages |
Flow and transport processes in porous media occur on different spatial and temporal scales and may also be locally different. Additionally, the structure of the porous medium itself generally shows a high dependence on the spatial scale.As an example, the contamination of the unsaturated zone with a light non-aqueous phase liquid is studied, corresponding to a domain with randomly distributed heterogeneities where complex three-phase–three-component processes are relevant only in a small (local) subdomain. This subdomain needs fine resolution as the complex processes are governed by small-scale effects. For a comprehensive fine-scale model taking into account three-phase–three-component processes as well as heterogeneities in the whole (global) model domain, data collection is expensive and computational time is long.Therefore, we developed a general multi-scale concept where on the one hand, the global flow field influences the local three-phase–three-component processes on the fine-scale. On the other hand, a coarse-scale saturation equation is solved where the effects of the fine-scale multi-phase–multi-component processes in the subdomain are captured by source/sink terms and the effects of fine-scale heterogeneities by a macrodispersion term.It turned out that the new multi-scale algorithm represents a flexible and extendable tool for incorporating processes of different complexity occurring at different locations in one model domain, while reducing the amount of required data. Using a simplified numerical example, it could be shown that the multi-scale algorithm functions very well. However, more research has to be done in order to further improve its computational efficiency.