Turbulent sediment transport using momentum balance — The strong turbulence approximation

The turbulent flow of a sediment-fluid mixture near a flat bottom is studied. An equation is derived expressing the balance between the gravitational force on the sediment and the turbulent sediment momentum flux. A mixing length theory is used to model the turbulent momentum flux, with the mixing lengths assumed proportional to the distance from the bottom. The ratio of the sediment momentum mixing length to the mixture momentum mixing length is assumed to be a universal constant. An approximate solution for the mean sediment flux profile is derived for situations where the turbulent strength near the bottom dominates the gravitational effects there. The resulting concentration profile is constant near the bottom and drops off rapidly above a certain predicted depth.