The influence of a deposit body on near-bed shear stress

The probability distribution of the fluctuating velocity in three dimensions and the near-bed shear stress (NBSS) of a channel with a deposit body were studied using mathematical statistics and the turbulent kinetic energy method, respectively. This analysis of the longitudinal and plane distributions of the NBSS under varying discharges, width ratios and lateral slopes will help further understanding of the laws of sediment incipient motion and transport in channels. It was found that the probability distribution of the near-bed vertical fluctuating velocity was closer to a normal distribution than that in the longitudinal and transversal directions. The NBSS did not change much in the upstream sections of the deposit body, but the difference between the left bank (near the deposit body) and the right bank (far away from the deposit body) was obvious in the sections near the deposit body and downstream. A high shear stress area was located in the transition zone between the main flow and the backflow. Introducing the backwater parameter β, an exponential relationship between the relative NBSS and β was determined, which will help in quick estimates of the NBSS in future practical projects.