BOUNDARY LAYER FLOW AND SAND TRANSPORT UNDER FULL SCALE SURFACE WAVES

Abstract

Existing models for wave-related (cross-shore) sand transport are primarily based on data from oscillatory flow tunnel experiments. However, theory and former experiments indicate that flow differences between full scale surface waves and oscillatory flow tunnels may have a substantial effect on the net sand transport. In this paper, high resolution measurements of boundary layer flow characteristics, sheet-flow layer sediment concentrations and net sand transport rates under full scale surface waves are presented. These experiments were performed in a large wave flume (GWK) for different wave conditions with medium (D50 = 0.25 mm) and fine (D50 = 0.14 mm) sand. It is shown that, especially under sheet-flow conditions, small wave induced net currents are of large importance for the total sand transport rates under these conditions.