Optical measurements of grain velocity and sediment concentration in shallow upland flows

This paper presents optical probe measurements on sediments in saltating flow in a laboratory flume for three particle sizes. Poly-dispersed sand particles exhibit greater resistance to the flow compared to the mono-dispersed glass beads. Cross-correlation of signals between twin Photonic probe data show smaller grain velocities with relatively higher solid concentration values due to grain collisions. However, turbulence modulation and reduction in the particle drag at relatively small solid concentration values depict acceleration of grains in a certain range. Grain velocity is correlated with the solid concentration, fall velocity, and the fluid Froude number.