OBSERVATIONS OF THE TURBULENT STRUCTURE OF A SUSPENSION OF SAND IN A TIDAL CURRENT

Measurements of the high-frequency fluctuations in the concentration o f sand suspended by a tidal current, taken simultaneously with high-fr equency measurements of the horizontal and vertical components of wate r velocity above the sandy bed of an estuary, have been used to examin e the turbulent structure of the suspension, the physical mechanisms w hich suspend the sediment, and the damping of the turbulent kinetic en ergy caused by the suspension. The turbulent ''bursting'' phenomenon i s found to play an important role in the suspension process.