DISTRIBUTION OF SUSPENDED SEDIMENT OVER WAVE-GENERATED RIPPLES

Oscillatory flow over wave ripples is described by use of a discrete v ortex model using the ''cloud in cell'' concept. The distribution of s uspended sediment over the ripple bed is simulated by a Lagrangian mod el, following the track of individual sediment particles. A boundary-l ayer model is used to determine the strength and the motion of the vor tices very close to the ripple, surface. The development of the bounda ry layer is described by the integrated momentum equation, assuming th e boundary layer to be turbulent with a logarithmic velocity profile. In the boundary layer, turbulent diffusion is used to describe the dis tribution of suspended sediment. Outside the boundary layer along the ripple surface, advection with the velocity field resolved by the disc rete vortex model determines the suspended-sediment distribution. The simulated sediment concentrations are compared to measurements from th e literature. The agreement between the time averaged simulated concen tration profiles and the measurements from an oscillating water tunnel is satisfactory.