Large Eddy Simulation of Suspended Sediment In Turbulent Open-Channel Flow

This study aims to shed light on the dark sides of sediment transport and meandering channel flow patterns. For this purpose, the Large Eddy Simulation methodology was used to investigate sediment transport in open-channel flow and also to predict the meandering channel flow pattern in two sine-generated channels. In the turbulent flows the transported suspended sediments is usually assumed in a passive form. In other word, the feedback effect of sediment suspension on near-wall momentum transport is neglectable. The first phase of this research was devoted to quantify the just mentioned effect in the open channel flow. A single phase approach was used to gain better description of sediment-turbulence interaction. The contribution of the small scales was parametrized by a dynamic Smagorinsky model. Results revealed that - in presence of large suspension- the buoyancy effect modifies the dynamics of flows. The second phase of the research was dedicated to the turbulent flow in meandering channels. These channels had initial deflection angles of 45 and 95 degrees. In both cases the width-to-depth ratio was equal to 15. The super-elevation of water in channel, which is impressed by secondary motion in the meandering channels, was considered in the numerical model. Analysis of numerical results was carried out on the basis of both instantaneous and time-averaged velocity fields. In addition, to provide an accurate description of the mean flow, this work explored the characterization of the cross-circulatory motion and the internal turbulence structure of flows. In particular, the sediment transport was investigated in the meandering channel to clarify the effect of bed shear stress variation induced by the channel curvature.