Spectral Analysis of Wave Reflection in Model Tests

Wind waves, which can travel beyond the direct effect of the generating forces, are reflected by beaches, breakwaters, shoreline structures and submerged or floating offshore structures. The interactions between reflected and incident waves contribute to the characteristics of the wave field and flow field beneath the waves. A laboratory study carried out to consider the reflection characteristics from the beach with a constant mild slope of a wave flume and a model vertical seawall using the two dimensional method of Goda and Suzuki (1976). An extensive series of experiments set up covering different regular, irregular and groupy waves to find the percentage of reflected waves. Two methods of 1) Averaging the reflection coefficient components 2) Using the power spectra of incident and reflected waves in a suitable range of frequency were employed to obtain the reflection coefficients. The results showed that in both methods the proper handling of spurious spikes is vital to get real results for reflection coefficient. The results also showed that the rate of reflection coefficient increases with an increase in fundamental wave frequency. However the reflection coefficient get larger for groupy waves with longer duration.