PERFORMANCE STUDY OF A LOW-PASS FILTER TO MODEL ENERGY DISSIPATION DUE TO MULTIDIRECTIONAL WAVE BREAKING IN HOS-NWT

The open-source available High Order Spectral – Numerical Wave Tank (HOS-NWT) (Ducrozet et al., 2012) is an extensively validated and widely used model to simulate waves in a wave basin. For instance, Vyzikas et al. (2021) proved a very good performance of HOS-NWT for the surface dynamics of steep focused wave groups. However, since the model is a free surface potential flow solver, modelling breaking waves within this framework is far from straightforward. Yet, if one’s interest is in capturing the effect of breaking on the overall wave-field evolution, rather than in deterministically replicating extreme breaking events, applying a simple low-pass filter in the wavenumber space could already give reasonable results (Slunyaev and Kokorina, 2020). The aim of this study is to verify the performance of such a low-pass filter to replicate the wave statistics in a numerical twin of the Coastal and Ocean Basin (COB) in Ostend (Belgium) for various sea states. To do so, experiments in the COB have been done on long- and short-crested waves of different steepness’s and peak periods. The realized paddle motions during these experiments are then used as input for the numerical twin of the COB based on HOS-NWT in which the low-pass filter proposed by Xiao et al. (2013) is included. By comparing the resulting wave statistic in the physical and numerical basins, it will be decided whether the low-pass filters give acceptable results for the practical applications envisaged for the numerical twin of the COB or if more elaborate breaking models need to be included.