Computation of bed-load sediment flux based on Lagrangian and Eulerian quantities

Bed-load fluxes were calculated for particle recording experiments carried out over a fixed-bed composed of two layers of glued particles and a range of shear velocity ratios from u*/u*c = 1.2 to u*/u*c = 1.8. Sediment fluxes were computed from a Lagrangian-Eulerian standpoint as proportional to entrainment rate and hop length, and from a purely Eulerian approach based on the multiplication of concentration of moving particles and their average Eulerian velocities. Results proved that if the experimental bias to the values of hop lengths is appropriately corrected, there is a perfect coincidence between the two methods, as the Lagrangian-Eulaerian and Eulerian sediment fluxes were identical for all the experimental conditions.

Keywords:

Lagrangian , Eulerian , sediment flux , entrainment , hop length