The interaction of oscillating-grid turbulence with a sediment layer

Abstract

This study described a preliminary experimental setup to identify how near-bed turbulence interacts with and moves sediment. The turbulence generated by a vertically oscillating grid was made to interact with a homogeneous horizontal sediment layer. Near-spherical particles were used throughout with two types of sediment at comparable sediment size d≈700 μm. The interaction characteristics were investigated by employing the PIV technique to measure the velocity field f the displaced sediment grains (within the transverse plane of the bed surface) during the interaction. Measurement of the velocity of the displaced sediment grains was restricted to the 1 case, where is the Shields parameter, the subscript denotes critical i.e. threshold criteria, τb is the mean bed shear stress and s relative density of sediment. During the period of interaction, the sediment grains were primarily displaced by the r dial velocities and formed distinctive circular trajectories. Energetic turbulence resuspends the particles above the bed surface, forming the characteristics particle splash. © Maxwell Scientific Organization, 2013.