Discovering Small Scale Controls on Bedload Flux through Lagrangian Simulations
Abstract
The dynamics of sediment particles moving in close contact with the bed has important implications for many physical and ecological processes in river channels. The analysis of the collective motion of particles is commonly predicted using formulas for the bedload flux based on empirical relationships that are function of global properties of the sediment and flow. At small scales, however, bedload transport is driven by nonlinear interactions of the sediment grains with the turbulent boundary layer, producing intermittent transport at low bed stresses. We seek to improve the prediction of bedload transport by studying the influence of the small-scale mechanics of sediment motion at larger scales. We carry out direct-numerical simulations (DNS) two-way coupled with a Lagrangian particle model to capture the details of sediment dynamics, and we upscale the bedload flux using a stochastic formulation to investigate the impact of fluctuations at larger temporal and spatial scales, as a function of the Shields parameter. This approach provides a new perspective on the prediction of bedload transport, based on insights provided by high-resolution simulations.
Work supported by Fondecyt grant 1191785- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP51B..03E
- Keywords:
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- 1810 Debris flow and landslides;
- HYDROLOGY;
- 1862 Sediment transport;
- HYDROLOGY;
- 1865 Soils;
- HYDROLOGY;
- 1899 General or miscellaneous;
- HYDROLOGY