Effects of Eddies on Heterogeneous Bimolecular Reactive Transport in Rough Fractures
Abstract
Subsurface flow and reactive transport in fractured geologic media often control important hydrogeologic processes such as subsurface nutrient transport and karst formation. Fracture network scale reactive transport is often controlled by single fracture scale processes, and pore-scale reactive transport modeling is an essential tool for improving mechanistic understanding of reactive transport processes at a single fracture scale. However, the interplay between fracture roughness, inertia, and diffusion makes the process of reactive transport very complex. For example, eddies are shown to trap solute particles and cause non-trivial effects on reactive transport. However, the effects of eddies have not been studied for heterogeneous reactions that take place on the fracture surface. In this study, we explore wide ranges of roughness, inertia, and diffusion regimes to advance our fundamental understanding of heterogeneous reactive transport in rough fractures. We first simulate irreversible heterogeneous bimolecular reactive transport using a particle tracking method. We inject A particles as reactants at the inlet and the infinite number of B particles are present at the fracture walls. When A particle hits a fracture surface, we generate a C particle as a product. With the reactive transport model, we investigated the transport of A and C particles at different levels of fracture roughness, Peclet (Pe), and Reynolds (Re) numbers. We found that eddies, which develop through the interplay between fracture roughness and Re, promote the reaction by increasing residence time of A particles near fracture walls and cause anomalous transport by increasing the residence time of C particles through trapping effects. However, the effects of eddies are shown to be very sensitive to Pe. The roughness also has strong effects because it determines the development of eddies. We finally propose an upscaled reactive transport model that effectively captures the reactive transport.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H33C..03L
- Keywords:
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- 1805 Computational hydrology;
- HYDROLOGY;
- 1822 Geomechanics;
- HYDROLOGY;
- 1829 Groundwater hydrology;
- HYDROLOGY;
- 1832 Groundwater transport;
- HYDROLOGY