Analysis of nonlinear ship-induced 3d wave fields using nonlinear fourier transforms

In the past decade, observations in the German estuaries such as the rivers Elbe and Weser show increasingly serious damage to bank protection structures (groins and revetments). This damage is caused mainly by waves induced by the passing of big container ships in the shallow and narrow maritime waterways. These ship-induced 3D wave fields consist of long-periodic primary and short-periodic secondary wave components. Due to missing design approaches for the load of long-period waves on rubble-mound revetments, the current risk assessment for protective structures in maritime waterways is based on short-period, wind-induced waves. Therefore, the structures do not ensure sufficient stability against the long-period ship-induced wave loads within the estuaries. Within the research project “Parameterization of nonlinear ship-induced 3D wave fields for the hydraulic design of protective structures in maritime waterways (PaNSiWa)”, we apply nonlinear Fourier transforms (NFTs) on experimentally generated ship waves in maritime waterways. The objective of the project is to provide better understanding of the underlying nonlinear structure of the long-period primary waves and to separate the nonlinear spectral basic components within the ship-wave data from their nonlinear wave-wave interactions. In this paper, we present first analyses of the decomposition of ship-wave measurements from experimental tests and the identification of hidden solitons within the long-period primary ship wave.