Velocity and Concentration Distributions in Sheet Flow above Plane Beds

This paper reports the results of experiments on particle-water flow over plane-topped stationary beds. The particles used were silica sands having d50 of 0.30 and 0.56 mm and Bakelite particles having d50 of 1.05 mm. The facility was a recirculating loop with pipe of 105-mm internal diameter. Data comprised measurements of hydraulic gradient, volumetric discharge, temperature, concentration profiles, velocity profiles, and delivered concentrations. The thickness of the sheet-flow layer is found to vary in proportion to the shear stress. The velocity at the top of the layer is found to be ∼9.4 times the shear velocity, and a simple relation expresses the velocity gradient at this height. The Richardson number at the top of the sheet flow averages ∼0.035, decreasing with increasing ratio of particle fall velocity to shear velocity.