Shear Stress Measurements and Erosion Implications for Wave and Combined Wave-Current Generated Flows

Abstract

Sediment transport in wave-dominated environments is of great interest for dredged material placement, contaminated sediments, habitat protection, and other issues. The shear stress at the sediment-water interface during a wave event is an important parameter in determining erosion and transport for both experimental and model simulation applications. Sandia National Laboratories has developed a laboratory and field device called the sediment erosion actuated by wave oscillations and linear flow (SEAWOLF) flume in which high-resolution, particle-image velocimetry (PIV) has been applied to investigate turbulent flow shear stresses for a variety of flow conditions. The results of the PIV analysis for a wave cycle demonstrate a fully developed turbulent flow, relaminarization, and an explosive transition back to turbulence. In many cases, the results of the flume tests did not show good agreement with previously reported computational fluid dynamic results and existing theories, such as Blasius, for wave-current interactions, which raises the question of whether similar phenomena are present in real environments. These results implore more studies to be conducted with similarly high-resolution field measurements and modeling efforts to determine shear stress time history for oscillatory flows and the subsequent effects on erosion and sediment transport in wave-dominated environments.