Sediment Suspension in Turbulent Pipe Flow

An analytical model of nonhomogenous low-concentration sediment suspension in turbulent flow of a liquid in a pipe is developed from the generalized, two-dimensional continuity-diffusion equation for suspended sediment. The equation is solved for the case in which the radial and azimuthal sediment fluxes are everywhere separately in balance, to yield a relation between the radial and azimuthal diffusion coefficients. The continuity equation is then solved for the case of homogeneous, isotropic diffusivity. The predicted exponential vertical distribution of sediment concentration was compared with results from five experiments in which concentration distributions were measured along seven radii. The experimental data were found to be in excellent conformity with the analytical results. The turbulent diffusion coefficient for sediment was found to be about 50% greater than that for momentum.