Velocity profiles for particles and liquid in open-channel flow with suspended sediment

Experiments were performed to measure the mean velocity and turbulence characteristics in open-channel flows with and without suspended sediment (alluvial sand of nearly uniform size). Velocity measurements were obtained by using a newly developed technique, the discriminator laser-doppler velocimeter (DLDV), which can distinguish both liquid and sediment particle velocities. The mean velocity of sediment particles was found to be lower than that of the water. While the velocity fluctuations in the water were not changed with the addition of sediment, those of the sediment were diminished. For the range of concentrations considered, the friction velocity and the free-surface slope increased with sediment concentration unlike other bulk flow parameters, which were practically constant. A uniform method of analysis was developed to facilitate data interpretation and comparison between similar studies.