A Lattice-Boltzmann model for simulating bedform-induced hyporheic exchange
Abstract
Bedform-induced hyporheic exchange plays a fundamental role in the ecohydrological and biogeochemical functioning of aquifer-river interfaces. The understanding of the complex interchange of hyporheic exchange fluxes, solute and energy transport between surface and groundwater is fundamental to design effective management, restoration and pollution mitigation strategies. For the first time, the Lattice-Boltzmann method was used to simulate 2D hyporheic exchange flow across a succession of dunes. The velocity field in both surface and groundwater was simulated directly; then, residence times were computed through post-processing. As a novelty to most previous applications of similar computational fluid dynamics models, a grid-independence test was performed for to analyse independence of the results from the mesh choice. The Lattice-Boltzmann simulation results are compared to previous fluid dynamic models of similar bedforms, and the impact of the bedform on hyporheic exchange flow dynamics is discussed. As an advantage, both the free-flow and the hyporheic exchange flow are simulated within the same model, thus removing the need of developing two distinct models as well as the coupling between them: the model dynamically reproduces turbulent Navier-Stokes (surface water) or generalized Darcian (groundwater) flow, depending only on the local value of the porosity field. Through this model, the critical advantages of the Lattice-Boltzmann method, consisting of unparalleled computational parsimony, meshing simplicity and attitude towards diffuse computing, are made available for a wide range of similar applications.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.H51L..02D
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0496 Water quality;
- BIOGEOSCIENCESDE: 1830 Groundwater/surface water interaction;
- HYDROLOGYDE: 1839 Hydrologic scaling;
- HYDROLOGY