Effects of Bed-load Transport on Turbulent Shear Stress
In open channel flows, the influences of sediment transport on overlying flow characteristics are not well understood. In particular, it is not clear how the non-cohesive sediment loads and overlying flows interacts and influences each other. In order to clarify the issue, two sets of experiments were carried out. One is to investigate the flow turbulence level over a rough impermeable bed without bed-load transport and another one in presence of bed-load transport. An Acoustic Doppler velocimeter (ADV) was used to measure the velocity in flows. The experimental results for bed-load transport over the rough impermeable bed reveals an excessive damping in Reynolds shear stress (RSS) distributions compared to that of flows without bed-load transport. Also, the experimental results shows that the bed-load transport significantly reduces turbulent kinetic energy dissipation rate in the near-bed flow zone which attributed to the damping in Reynolds shear stress (RSS) distributions in comparison to flow conditions of without bed-load transport and diminishes monotonically away from the bed surface.
Keywords - Bed-Load, Open-Channel Flow, Reynolds Shear Stress.