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LARGE-SCALE TURBULENCE GENERATION AND MICROBREAKING WAVES

Ira Leifer
Chemical Engineering Department University of California, Santa Barbara, California 93106 USA

Brian D. Piorek
Chemical Engineering Department University of California, Santa Barbara, California 93106 USA

Walter C. Smith
Chemical Engineering Department University of California, Santa Barbara, California 93106 USA

Sanjoy Banerjee
Department of Chemical Engineering University of California at Santa Barbara, Santa Barbara, California, 93106

Resumo

Observations in a wind-wave channel show that microbreaking waves are distinguished by the generation of large and persistent turbulence bursts, a shear layer, a convergence zone in front of the crest and a divergence region behind the crest. Burst persistence was measured at different wind speeds, 1.5 and 2.5 m s−1. The lower wind speed gives rise to occasional microbreaking, which was far more frequent at the higher wind speed. The results show that microbreaking causes a change in the burst persistence probability distribution. For the lower wind speed, persistence decreased monotonically, while at higher wind speeds it was bimodal with an additional peak at 0.25 s. This suggests a qualitative change in turbulence structure in the subsurface region caused by microbreaking.