Accession Number : ADA298657

Title :   Directional Spreading Effects on Nonlinear Waves Shoaling on Beaches.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Burton, Mark C.

PDF Url : ADA298657

Report Date : JUN 1995

Pagination or Media Count : 53

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. (AN)

Descriptors :   *OCEAN WAVES, *BEACHES, *GRAVITY WAVES, MATHEMATICAL MODELS, FOURIER TRANSFORMATION, OCEAN CURRENTS, OCEAN SURFACE, TWO DIMENSIONAL, THESES, DEPTH, FINITE DIFFERENCE THEORY, MATHEMATICAL PREDICTION, WAVE PROPAGATION, APPROXIMATION(MATHEMATICS), SLOPE, PARTIAL DIFFERENTIAL EQUATIONS, WIND VELOCITY, NONLINEAR ANALYSIS, AIR WATER INTERACTIONS, LITTORAL ZONES, SPECIAL FUNCTIONS(MATHEMATICS), OCEAN MODELS, SHORES.

Subject Categories : Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE