Characterization of turbulence in natural bed flows is very complex and highly important owing to its numerous application in the field of sediment transport. In the present work a turbulent open-channel flow experiment, with a natural pebble bed at Re = 4.65 × 104 and Fr = 0.186, has been numerically simulated by means of the Large Eddy Simulation (LES) approach, in which the Wall-Adapting Local Eddy viscosity (WALE) subgrid scale (SGS) closure model is used. The simulations have been compared with a companion experiment, where the channel bottom is constituted by four natural-pebble layers. For the simulations, the pebble-bed surface has been captured with a high-resolution three-dimensional (3D) laser scanner and used to morphologically characterize the bottom of the numerical channel. Results are presented in terms of turbulence statistics and turbulent laws, showing a good agreement with those obtained in the companion experiment. A procedure for vortex-visualization is presented, based on the relationship between the vorticity and the Turbulent Kinetic Energy (TKE) dissipation rate.
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