Unsteady two-dimensional distribution of suspended sediment transport in open channels

The current work presents a two-dimensional (2D) unsteady suspended sediment transport model for an open channel turbulent flow. Unlike most of the existing similar works in literature who describes either the spatial change or the temporal change in concentration along with vertical distribution, the present study describes spatial, temporal and vertical variation of concentration together. The model is developed from the mixing length point of view, which is an important feature of turbulent flow. It also incorporates the effect of hindered settling velocity of a sediment particle resulting from the presence of other particles in the flow. The developed non-linear partial differential equation together with the most realistic boundary condition has been solved numerically. The findings indicate that the suspension region experiences a decrease in concentration value far from downstream as a result of the modified mixing length of sediment-laden flow and opposite is the case for the hindered settling velocity at any downstream position. Over all, a reduction in the concentration value occurs in the suspension due to the inclusion of these two effects. Also, the hindered settling increases the magnitude of the bottom concentration and the damping factor of mixing length decreases the magnitude of the bottom concentration both the effects being very small. The model has been validated with laboratory data under specified conditions.