. DUCK85 surf zone sand transport experiment . Figure 7. DUCK85 streamer nozzle 23. Based on the results of a uniform-flow tank experiment conducted following the field project (Rosati and Kraus 1988), the streamer trap nozzle used at DUCK85 is no longer recommended. This test examined the hydraulic efficiencies of 22 generic nozzle configurations plus several variations and led to an improved design that has been used in later field data collection projects such as SUPERDUCK. 24. In addition, sand-trapping efficiency tests in uniform flow were performed in another series of experiments (Rosat
. DUCK85 surf zone sand transport experiment . Figure 7. DUCK85 streamer nozzle 23. Based on the results of a uniform-flow tank experiment conducted following the field project (Rosati and Kraus 1988), the streamer trap nozzle used at DUCK85 is no longer recommended. This test examined the hydraulic efficiencies of 22 generic nozzle configurations plus several variations and led to an improved design that has been used in later field data collection projects such as SUPERDUCK. 24. In addition, sand-trapping efficiency tests in uniform flow were performed in another series of experiments (Rosati and Kraus in preparation) for a small number of nozzle configurations which had near optimal hydraulic efficiencies, including the DUCK85 nozzle. It was found that the DUCK85 nozzle had a sand-trapping efficiency near unity () for suspended sand, but a much lower efficiency for a nozzle resting on the bed (). The small value () of the bed-load trapping efficiency (which includes suspended load within 9 cm of the bottom) is caused by scour and the scour hole created under the nozzle, allowing sediment to pass under it. Other nozzle designs, which replace the 1/4-in. rods with sheet metal hoods essentially eliminate this problem for uniform flow conditions. The actual efficiency of the 19
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