Sediment‐induced stratification in turbulent open‐channel flow

A vertical gradient of suspended sediment concentration exists in a turbulent open channel flow, particularly near the bed where sediment erosion and deposition take place. This shows a remarkable effect on the flow dynamics. The density gradient of sediment‐mixed fluid may become stably stratified, which results in damping of turbulence fluctuations. In this work, theoretical models for mean velocity and concentration distributions have been developed considering the effect of sediment‐induced stratification and the modified mixing length due to high suspension together with viscous and turbulent shear stresses, which are the functions of concentration. The models are compared with comprehensive experimental data sets. The comparison reveals that (i) the calculated velocity and concentration profiles agree well with the observed data, (ii) the model constant due to stratification used for verification is consistent with the measurements in thermally stratified flows, and (iii) the higher the sediment suspension, the better the effect of density stratification and the less the impact of mixing length.