Author(s): Anurag Sharma, Bimlesh Kumar
Linked Author(s): ANURAG SHARMA
Keywords: Reynolds shear stress, seepage, sediment transport, velocity
Abstract: The present study focuses on the influence of downward seepage flow on the turbulent flow characteristics over non uniform sand bed channel. Experiments are conducted for free-surface flows subjected to downward seepage from the boundary. The experimental result will deliver important information related to the turbulence characteristics, such as velocity, Reynolds shear stress, turbulent intensity and conditional Reynolds shear stresses. Reynolds shear stress increases along the channel bed are associated with the provided momentum from the flow to maintain sediment transport overcoming the bed resistance and then again decrease towards the boundary because of the presence of a roughness sub layer in the near bed region. The profiles of Reynolds shear stress is slightly scattered in general and increase with seepage which signifies the greater momentum transfer towards the boundary. The variations of stream wise velocity with vertical distance in flows with downward seepage in the near bed region are greater than no seepage flow. The thickness of roughness sub layer and shear velocities increase with seepage. The reduced value of von Karman's constant corresponds to increase in the bed load transport with seepage. In the presence of seepage, stream wise and vertical turbulence intensities increase compared to turbulence intensities in no-seepage. The anisotropy of turbulence is strong being seepage independent and varying approximately linear with flow depth. In quadrant analysis, the contribution of sweep events towards Reynolds shear stress production near the boundary increases with increased zone of sweep dominance. The mean time of occurrence of ejections and that of sweeps in seepage are longer than those in no-seepage
Year: 2017