Directional Spreading Effects on Nonlinear Waves Shoaling on Beaches.
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1995
- Accession Number
- ADA298657
Entities
People
- Mark C. Burton
Organizations
- Naval Postgraduate School