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|Wind-generated waves for laboratory studies
|Harris, D. Lee, 1916-
|Coastal Engineering Research Center (U.S.)
|Technical paper;no. 76-12
|Abstract: Mechanically generated, regular waves are used in laboratory wave basins and channels for testing engineering designs for the coastal zone. Wind-generated waves in the laboratory display irregularity, suggestive of the irregularity of the open sea. It has been suggested that the validity of laboratory tests would be increased if the laboratory waves were generated by wind. Examination of a simple approach to wave forecasting, based on dimensional analysis, leads to the conclusion that wind-generated waves in the laboratory cannot be expected to have the same form as prototype waves unless they correspond to equivalent scaled fetches. Very low windspeeds must be used to produce waves that are anywhere near fully developed in a laboratory facility of moderate length. The resulting waves are too small to be of much value in testing designs. An examination of the microscale procedures, now believed to be responsible for wave growth and of some-secondary flow characteristics of wind tunnels, indicates that the relative importance of the mechanisms for wave generation in wind channels is very different from that in unconfined airspaces. Modeling the effects of nearshore wind in modifying waves generated far from shore may be possible if the waveform, as it exists at a modest distance from shore, can be modeled by a mechanical wave generator. If modeling the offshore wave is possible, direct mechanical generation of the desired form may be easier and more economical than adding a wind tunnel above the wave channel. Laboratory wind-wave research facilities can be useful for basic research concerning air-sea interaction even though they are of doubtful value in testing engineering designs.
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|CERC Technical Paper No 76-12.pdf