Author(s): Vaclav Matousek; Jan Krupicka; Tomas Picek; Lukas Svoboda; Stepan Zrostlik

Linked Author(s): Vaclav Matousek, jan krupicka, tomas picek

Keywords: Combined load transport; Sheet flow; Tilting flume experiment

Abstract: Steady uniform open-channel flow with intense transport of combined load (suspended load and contact load) above plane mobile bed is modelled using a new developed transport model based on the kinetic theory of granular flow. The model is an extension of the recently developed model for collisional transport and the new model employs the mixing-length concept to incorporate a contribution of flow turbulence in supporting transported sediment particles additional to the dominating support contribution by interparticle contacts. The model predicts flow rates of water and sediment for a given combination of the channel depth and longitudinal slope and includes predictions of the solids distribution and flow velocity across the flow depth. Validation experiments with lightweight sediment in a laboratory tilting flume provide results for a comparison with new model predictions. The experiments include measurements of the distribution of the local sediment concentration using the camera-based laser stripe technique and measurements of the distribution of velocity of solids using the imaging technique based on Particle Tracking Velocimetry with two synchronized high-speed cameras. Furthermore, local velocities of water are obtained from Pitot-tube measurements. The paper presents results of the transport model and their comparison with results of the laboratory experiment for a relatively broad range of bed shear conditions (Shields parameter between 0.8 and 1.8 approximately). A discussion includes criteria and conditions for the local support of sediment particles by turbulent eddies in the transport layer of the flow transporting combined load.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221037

Year: 2022