Correlating Seabed Drifter Weights to Sand Threshold Conditions in Wave andWave/Current Environments

摘要

The purpose of this study was to investigate the response of seabed drifters(SBD' s) to combined waves and currents and, specifically, to examine the feasibility of modifying these bottom current drogues to behave more like sediment particles. This is the only known full-scale, quantitative study of the response of SBD's to wave and current forces. Standard design SED's were modified by changing the attached weight so that the SBD's would move on the seafloor only when the flow conditions were sufficiently vigorous to initiate sediment motion. Relative drag and inertia coefficients for SBD's were evaluated and related to the Reynolds numbers and the Keulegan-Carpenter parameter. Using these relationships, a methodology was derived for selecting threshold SED weightings appropriate for different situations. The SBD's used in these tests were identical to those used in recently reported studies conducted by the U.S. Army Corps of Engineers at Duck, NC, Sand Island, AL, and Humboldt, CA.