Sediment erosion in zero-mean-shear turbulence
Résumé
A stirring grid, in a square tank, located more than 2 mesh sizes away from a sediment layer, is used to study particle
erosion by a zero-mean-shear turbulence. The particle concentration has been monitored using an OBS technique and
fluid velocity mostly through PIV. Particle lift-off and concentration in the tank are shown to rise sharply as the grid
frequency is increased. Converged velocity profiles indicate that the bulk isotropy of the turbulent velocity in the tank,
well predicted by a slightly modified Matsunaga et al. (1999) model, gets broken close to the bed. While mean shear
rates are shown to be small at the bed surface, some high shear level events induced by vortex impacts are assumed to
be responsible for the particle erosion.