Downward spreading of turbulence beneath breaking waves and its influence on sediment suspension

Abstract

When waves start breaking, in the nearshore zone, turbulence is injected at the surface by the breaking waves. Under these conditions, turbulence can also have an influence on the bed. Turbulence generated at the surface can penetrate through the water column and at the bed, provide an additional mechanism to suspend sediment. Presently, bed sediment transport is parameterised in terms of the wave height or orbital velocity to the power 3. This parameterisation does not seem to be applicable to sediment transport under breaking waves, as this parameterisation is based on the assumption that sediment is suspended by near-bed processes, while surface-generated turbulence is not taken into account. Therefore, the characteristics of turbulent kinetic energy during different conditions are investigated. Furthermore, the turbulent kinetic energy will be related to the sediment suspension.