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Title: Orbital velocity associated with wave action near the breaker zone
Authors: Scripps Institution of Oceanography
United States. Army. Office of the Chief of Engineers
Inman, Douglas Lamar, 1920-
Nasu, Noriyuki
Keywords: Orbital velocity
Wave action
Water waves
La Jolla, California
Sand transport
Beach erosion
Publisher: United States, Beach Erosion Board
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical memorandum (United States. Beach Erosion Board) ; no. 79.
Description: Technical Memorandum
Abstract: The orbital velocity associated with ocean surface waves in shallow water was aeasured for various wave conditions at La Jolla, California, as part of a program of study of sand transport and beach erosion. The measuremeDts were made near the bottom and just seaward of the breaker zone in water depths ranging from about five to fifteen feet and for wave heights as great as seven and one-half feet. The current measuring device consisted essentially of a cylindrical rod fixed rigidly at one end like a cantilever, and the system was so arranged that the orbital velocity could be interpreted froa the bending of the rod caused by the force exerted by the moving water. Orbital velocity and wave pressure were recorded simultaneously for time intervals of about twenty minutes. The observed aaximum horizontal velocities compare favorably with velocities predicted from solitary wave theory for most waves with simple profiles when the ratio of the wave height to water depth is greater than about 0.4. The agreement with theory is somewhat better for longer period waves, and in some cases is still quite good in regions where the ratio of wave height to water depth is less than about 0.2. On the average, the onshore veloci ty associated with the passage of a wave crest was greater in magnitude and of shorter duration than the off shore velocity under the wave trough. The differences in crest and trough velocities varied from wave to wave, but in general correlated with the shape of the waves.
Appears in Collections:Technical Memorandum

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