Validation Of A Nonlinear Wave Decompistion Method Including Shoaling

Abstract

It is important to decompose the incident and the reflected waves when performing physical or numerical experiments in a wave flume. Especially when large reflection is expected, from for example a breakwater, the total measured signal can significantly deviate from the incident signal.

Different techniques exist to decompose a signal into incident and reflected signals. For 1D wave flumes a method based on co-located wave gauges (Nwogu, 1989) or multiple wave gauges (Røge Eldrup and Lykke Andersen, 2019, Zelt and Skjelbreia, 1993) is commonly applied. The latter is the focus of this abstract since recently, the decomposition method based on multiple wave gauges was extended to be applicable to nonlinear irregular waves by including bound waves and amplitude dispersion (Eldrup and Lykke Andersen, 2019). Moreover, the practical requirements for the nonlinear wave decomposition methods were described in De Ridder et al. (2023).

Most of the nonlinear wave decomposition methods are only applicable to a flat bed and will introduce an error when it is applied on a sloping foreshore which is typically the case in physical model experiments. Padilla and Alsina (2020) derived a general framework including shoaling of bound waves and Lykke Andersen and Eldrup (2021) presented a method for nonlinear regular waves over a sloping bed. However, a nonlinear decomposition method for irregular waves over a sloping bed has never been verified with physical model experiments.

In this abstract the nonlinear decomposition method for irregular waves as presented in De Ridder et al. (2023) is extended with the effects of shoaling and its effects are verified with a physical model experiment.