A ship in motion generates a complex wave field consisting of several superimposed wave systems. The relevance of the wave systems' components varies, depending on individual ship and waterway parameters. This review work is specifically concerned with the long-period, primary wave system, large-volume ships travelling through confined waterways, generate, as it may exert intensive wave and current loading on the banks, affecting local morphology, engineering structures and ecology So far, the effect of ship-generated waves on waterway embankments has yet only routinely been considered for inland waterways with a constant cross-section. Less attention has been payed to the ship-induced wave and current loading in more complex bathymetries like coastal waterways and estuaries, as naturally occurring loads had been thought to dominate. However, the hydrodynamic loads induced by ships grow and become increasingly relevant in coastal waterways, due to continuously growing dimensions of sea-going ships. At the same time, requirements rise to allow for restoring the ecological value of of inland and coastal waterways, leading to spatially more diverse bathymetries and embankment structures. Hence, the prediction of ship-generated primary wave magnitudes at banks becomes increasingly complex, due to deformation processes of the propagating waves in shallow water. Knowledge on ship-generated waves characteristics and methods to predict induced loads are thus essential for the assessment of bank stability and the dimensioning of engineering structures to resist present-day and prospective ship-induced loads. This review paper compiles, analyzes and assesses the findings of previous research quantifying the relevance of primary waves for the surrounding waterways and shows interconnections to the questions studied within naval hydrodynamics for confined waterways. Commonly applied methods for wave prediction are reviewed, highlighting their relevance and limitations. Finally, a concept for coupled numerical model development is suggested, based on the success of different modelling approaches presented previously.

This work analyzes the propagation properties of long-period ship-induced waves of vessels in confined waterways that are surrounded by wide and shallow water bodies using numerical simulations. Previous measurements indicated that, in the presence of shallow water surroundings, the drawdown being part of the long-period wave system can travel in the form of depression waves over several ship lengths distance [Parnell et al., “Ship-induced solitary Riemann waves of depression in Venice Lagoon,” Phys. Lett. A 379, 555–559 (2015); Scarpa et al., “The effects of ship wakes in the Venice Lagoon and implications for the sustainability of shipping in coastal waters,” Sci. Rep. 9, 19014 (2019)]. The exact conditions leading to these unexpectedly large propagation distances could to date not be clarified [Parnell et al., “Depression Waves Generated by Large Ships in the Venice Lagoon,” J. Coastal Res. 75, 907–911 (2016)]. In this work, evidence from numerical simulations is presented, indicating that the far-field propagation properties are governed by the wave speed of the shallow water surroundings. In case the ship speed is larger than the surrounding wave speed (supercritical conditions), a free wave is continuously generated traveling over the shallow water with only minimal height decay. In the simulations, depression waves can travel over a distance of three ship-lengths with a height reduction below 10% in the supercritical regime, as compared to 80% height reduction in the sub-critical regime. In a one-dimensional environment, this agreement of free and forced wave speed is known as Proudman resonance.

In recent years, increasing ship sizes and associated increasing wave loads have led to a demand for prediction tools quantifying the ship-induced loads on waterways. Depth-averaged numerical models, using a free-surface pressure term, are a prominent method to obtain the relevant design parameters. These models incorporate the wave deformation processes due to attributes of complex bathymetries, while allowing for an efficient simulation of large computational domains. The nonhydrostatic shallow-water-equations (SWE) model REEF3D::SFLOW uses a quadratic pressure approximation and high-order discretization schemes. This paper presents the implementation of a pressure term to account for the displacement of the free surface by solid moving objects. Two test cases verifying the implementation are shown based upon the analytical one-dimensional solution of the wave propagation due to surface pressure and the estimation of Havelock angles. These verification tests are the first step toward a holistic model, combining a large scale model with computational fluid dynamics (CFD) simulations near waterway banks.