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Surface-wave diffraction by a periodic row of submerged ducts

Published online by Cambridge University Press:  20 April 2006

John W. Miles
John W. Miles
Affiliation:
Institute of Geophysics and Planetary Physics, University of California, San Diego
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Abstract

The diffraction of a gravity wave of length λ that is obliquely incident upon, and the radiation from, a periodic row of vertical circular ducts of radii a and horizontal spacing b with mouths at a distance h below the free surface of a deep ocean are determined through integral-equation and variational formulations. Numerical results for the reflection coefficient, the pressure-amplification factor (the ratio of the complex amplitude of the wave-induced pressure in the depths of the duct to that of the incident wave at the level of the mouths), and the radiation impedance (the real and imaginary parts of which are measures of the radiation damping and the virtual mass or stiffness of the fluid external to the ducts) are presented as functions of a/λ with a/b and a/h as parameters for the special case of normal incidence with λ > b (which implies that the crests of the scattered waves are parallel to the midplane of the ducts). These results, which complement those of Simon (1981) for a single duct, are of practical interest for wave-power absorption.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 128 , March 1983 , pp. 155 - 180
Copyright
© 1983 Cambridge University Press

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