Author(s): Cristian Escauriaza; Magdalena Barros
Linked Author(s):
Keywords: Bedload transport; LES; Lagrangian model; Turbulence
Abstract: Bedload transport is driven by complex interactions between near-bed turbulence, grain-scale dynamics, and large-scale coherent structures. When local instantaneous hydrodynamic forces overcome resistive forces, they initiate sediment motion transporting grains downstream. In fluvial systems with large immobile boulders, flow separation and unsteady wake dynamics further modulate transport by sheltering or exposing mobile sediments. To investigate these processes, we employ large-eddy simulations (LES) with an immersed boundary method, using the double-averaging (DA) approach to quantify the small-scale effects on global momentum and energy budgets, including form-induced stresses that control bedload fluxes. The 3D flow simulations are coupled to a Lagrangian particle model based on the discrete element method (DEM) to simulate mobile sediments and characterize the temporal and spatial variability of particle velocity and activity, providing a statistical description of bedload fluxes to connect the small dynamic scales to large-scale transport.
Year: 2025