Erosion Control of Scour during Construction. Report 5. Experimental Measurements of Refraction and Diffraction Downcoast of an Oblique Breakwater

摘要

The present state of nearshore current and wave theories has reached the point where detailed experimental investigations are required for the verification of analytical developments and numerical models. To provide a foundation for further advancements, a simple beach profile consisting of straight, uniform contours parallel with the shoreline was experimentally studied by Hales (1980). A shore-connected, vertical, thin, impermeable barrier (break-water) was installed perpendicular to the shoreline to simulate prototype jetties and breakwaters commonly occurring along many coasts. The purpose of the present study is to extend the previous work of Hales (1980) by installing a shore-connected, vertical, thin, impermeable breakwater at a 60-deg angle to shoreline to simulate a larger range of prototype jetties and breakwaters in existence at the present time. Experimental measurements of refraction and diffraction downcoast of this oblique structure were made to obtain quantitative knowledge of this phenomenon in the lee of the jetty or shore-connected breakwater. These data were then compared with the uniformly valid asymptotic theory of Liu, Lozano, and Pantazaras (1979) for the same arrangement. A numerical model for determining wave heights downcoast of a straight breakwater at an angle to the shoreline under combined refraction and diffraction, based on the uniformly valid asymptotic theory, was compared with the experimental data.