Experimental investigation of turbulence effects on sediment pickup rate in open channel flows
Date of Issue2014
School of Civil and Environmental Engineering
Nanyang Environment and Water Research Institute
Laboratory experiments were conducted to measure the sediment pickup rate in open-channel flows with and without externally-generated turbulence. Experiments were conducted under four kinds of flow conditions: (1) uniform flow without any obstruction, (2) flow obstructed by a horizontal pipe placed above the bed, (3) flow obstructed by a vertical pipe located at the centerline of the channel and (4) flow over two-dimensional fixed dunes. Three uniform sediment particles with D50 = 0.23, 0.44 and 0.86 mm were used for pickup experiments and the flow velocity and turbulence were measured by a 3D down-looking Acoustic Doppler Velocimeter (ADV). Dimensional analyses were performed for all the experimental data resulting in empirical pickup functions based on both near-bed and bulk flow parameters. For the experiments under the undisturbed uniform flow conditions, the pickup rate could be well represented by both near-bed and depth averaged flow parameters. However, in nonuniform flows, the pickup function was proposed based only on bulk flow parameters.
DRNTU::Engineering::Civil engineering::Water resources