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On sound generation by weakly nonlinear interactions of surface gravity waves

Published online by Cambridge University Press:  21 April 2006

Y. P. Guo
Y. P. Guo
Affiliation:
Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK
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Abstract

The theory of sound generation by weakly nonlinearly interacting ocean surface waves is examined. The main conclusion is that this mechanism may not be a strong generator of ocean sound. It is shown that at low frequency and with small wind the sound generated by this mechanism is weak in comparison with that directly radiated by the turbulent airflow, the flow which is also the cause of surface waves. With increasing frequency and/or wind speed, the sound from surface-wave interactions becomes appreciable, but it is found that the condition for this sound overwhelming the aerial turbulence radiation implies the precise condition at which fully nonlinear surface motions occur. In that case processes such as splashing of water sprays by breaking waves become the main cause of ocean noise. In fact it seems that the weakly nonlinear mechanism proposed by Brekhovskikh is never an important source of sound in the real ocean.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 181 , August 1987 , pp. 311 - 328
Copyright
© 1987 Cambridge University Press

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