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Generation of Harmonics by Non-Breaking Water Waves Over Permeable Submerged Breakwaters

Published online by Cambridge University Press:  05 May 2011

Chao-Lung Ting  and
Ming-Chung Lin
Chao-Lung Ting*
Affiliation:
Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei, Taiwan 106, R.O.C.
Ming-Chung Lin*
Affiliation:
Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei, Taiwan 106, R.O.C.
*
**Associate Professor
*Professor
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Abstract

This work examines the interesting phenomenon of the generation of harmonics by non-breaking waves over permeable submerged obstacles. Nine model geometries, each with six different porosities, from 0.421 to 0.912, were considered to examine the effects of model width, porosity, and submergence depth on harmonic generation. The results revealed coupled effects on harmonic generation. A modified Ursell number was proposed to analyze experimental data. Almost no harmonic generation occurs at a modified Ursell number of less than five and/or a model width to wavelength ratio of over 1.6. After harmonics have been generated, wave profiles become dimpled, and the energy of the fundamental mode is transferred to higher-frequency components. Furthermore, the higher harmonics become more pronounced as the models widen, the depth of submergence becomes shallower, and model porosity declines.

Keywords

Harmonic generationporosity effectpermeable submerged breakwater
Type
Articles
Information
Journal of Mechanics , Volume 20 , Issue 1 , March 2004 , pp. 57 - 67
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2004

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