Directional spreading effects on nonlinear waves shoaling on beaches
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Authors
Burton, Mark C.
Subjects
Advisors
Herbers, T.H.C.
Date of Issue
1995-06
Date
June 1995
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
A nonlinear Boussinesq model for the shoaling of ocean surface gravity waves on beaches is presented and compared to second-order finite depth theory. The spectral Boussinesq model of Freilich and Guza (1984) for uni- directional waves propagating perpendicular to a beach with straight and parallel depth contours is extended to obliquely propagating waves. Predictions of the shoaling evolution of a single resonant triad with two primary incident wave components driving a secondary wave component are compared to finite depth theory predictions of forced secondary waves. Results for both sum- and difference-interactions are presented for a range of beach slopes, incident wave amplitudes, frequencies and propagation directions. The comparisons show that there is a region (roughly between 10 and 4 m depth for typical swell amplitudes and frequencies) where both theories predict very similar growth of secondary wave components. Whereas Boussinesq theory typically predicts slightly smaller secondary wave amplitudes than finite depth theory the dependence of the secondary wave response on the directional spreading angle of the primary waves predicted by both theories are in good agreement. However, pronounced discrepancies between Boussinesq and finite depth predictions are noted for very low waves on relatively steep beaches.
Type
Thesis
Description
Series/Report No
Department
Physical Oceanography
Organization
Identifiers
NPS Report Number
Sponsors
Funder
NA
Format
41 p.
Citation
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.