Vertical Distribution of Suspended Sediment in Uniform Open‐Channel Flow

The vertical distribution of suspended sediment in an open channel is studied theoretically by means of a new mixing length concept. The diffusion coefficient is represented as a function of the distance from the bed and dependent on the magnitude of sediment concentration. An equation to predict the sediment concentration is derived analytically, using the vertical mass-balance equation over the water depth. The theoretical concentration distributions are compared with previous experimental data. It is found that the present theory is applicable to sediment-laden flow with low and high concentrations. The ratio of the diffusion coefficient and the eddy viscosity, γ, is larger than unity and increases monotonically with the increase of the sediment load in flows with low sediment concentrations, and smaller than unity and decreases with the increase of the sediment load in flows with high sediment concentrations.