Non-Fickian Tracer Dispersion in a 3D Heterogeneous Model Porous Medium
Abstract
We experimentally and numerically study the dispersion of conservative tracers bromide and flourescein in a constructed dual-porosity porous medium. The medium consists of spherical low-hydraulic conductivity inclusions, embedded in a high-hydraulic conductivity matrix. System behavior is modeled with direct numerical simulations on the Darcy scale and upscaled two-region mass transfer models obtained using volume averaging. Transport processes in the experimental and numerical results can be described by three distinct characteristic time scales for: (i) convective transport in the high-conductivity matrix; (ii) diffusive transport in the low-conductivity inclusions; and (iii) convection within the inclusions. The volume-averaged effective macroscale dispersion coefficient computed for a unit cell accurately captures the transition from early-time breakthrough to tailing. We place special emphasis on the modeling of the late-time breakthrough behavior of the tracers, which is predicted qualitatively and quantitatively by both Darcy scale and volume averaged models.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.H51D1523V
- Keywords:
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- 1009 Geochemical modeling;
- GEOCHEMISTRYDE: 1832 Groundwater transport;
- HYDROLOGYDE: 1869 Stochastic hydrology;
- HYDROLOGY