Experimental study for decomposition of higher harmonic waves over submerged structure using four wave gages

Abstract

A detailed and intelligent investigation of the transformation of incident waves is necessary to design and protect coastal structures. And decomposition of waves into incident and reflected waves including higher modes has been recognized as significant work. In this study, we have conducted the experiments about the separation of waves using four wave gages method proposed by Lin and Huang (2004) in hydraulic laboratory. Based on this method, the fundamental wave modes and higher wave modes (locked and free) were obtained using the Fourier transform and least square method. In regular wave experimental conditions, the incident wave period was varied from 1.0 to 3.0 sec with an increment of 0.2 sec and one incident wave height of 0.05 m and 0.10 m was selected. And three different widths and two different heights of a submerged structure were used. We found that the transmission coefficient was higher for short and long wave periods than for the middle of a wave period when the width of a submerged structure became larger.