Effect of stratification due to suspended sand on velocity and concentration distribution in unidirectional flows

Sediment‐induced stratification effects on velocity profiles and sediment concentration distribution in a steady, uniform turbulent flow are examined in this paper. The early work concerning sediment stratification relates this to the von Karman constant's variability. Subsequent attempts to account for stratification were based on the stratified flow analogy, introducing the parameters α and β , whose values were assumed to be those obtained for thermally stratified flows. Following these investigators, we assume stratification effects to be expressed through these parameters. We solve the governing equations for velocity and sediment concentration for a parabolic neutral eddy viscosity model. Analytically closed‐form solutions are obtained. We run our model against experimental data to obtain the optimal set [ α , β ]. For neutral conditions, β = 0 by definition, and we obtain α = 1. For stratified conditions we obtain [ α = 0.8, β = 4.0]. This is the first time both α and β have been obtained from sediment‐laden flow observations. Accounting for stratification improves the prediction of velocity and concentration. For predictive purposes, we need to know the movable bed roughness and the reference concentration. Analyses of experimental data sets provide predictive relationships for these in terms of sediment and flow parameters.