  The present study revisits the vertical distribution of suspended sediment
concentration in an open channel flow with a special attention to sediment
diffusion coefficient. If turbulent diffusivity is considered to follow a
parabolic-type profile, the diffusivity coefficient is zero at the bed and very
small near the bed; so alone it may not be enough to diffuse the particles from
bed-load layer to suspension region. Leighton & Acrivos (J. Fluid Mech., vol.
181, 1987, pp. 415-439) introduced the idea of shear-induced diffusion that
arises due to the hydrodynamic interactions between solid particles. This work
considers the Hunt diffusion equation incorporating the concept of
shear-induced diffusion and reinvestigates the vertical sediment concentration
profile. Analytical solution is derived using a non-perturbation approach,
namely Homotopy Analysis Method (HAM), and is verified with numerical solution
as well as compared with available experimental data. The behaviour of the
shear-induced diffusion coefficient with vertical distance and varying particle
diameters have been interpreted physically. In addition, the effects of
important turbulent factors such as inverse of Schmidt number, hindered
settling velocity on concentration profile, have been investigated considering
relevant sets of experimental data.
