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This paper explores the variability of wave power in space and time using a 42-year high-resolution hindcast wave model from the Copernicus Marine Environment Monitoring Service for the North-West European shelf. We calculate the wave energy flux using significant wave height and wave energy period. To improve wave power assessment, we use knowledge about mean wavelengths and bathymetry, which is necessary given the nature of the intermediate and shallow waters in the region. The results provide monthly, seasonal, and inter-annual estimates of wave power variability based on 122,728 modeled wave measurements. The study advances the understanding of wave energy resources within the domain.

The study of wave‐structure interactions involving nonlinear forces would often make use of the popular hybrid frequency–time domain method. In the hybrid method, the frequency‐domain analysis could firstly provide the reliable and accurate dynamic parameters and responses; then these parameters and responses are transformed to the parameters to establishing the basic time domain equation. Additionally, with the addition of the required linear and nonlinear forces, the time‐domain analysis can be used to solve for the practical problems. However, the transformation from the frequency domain to the time domain is not straightforward, and the implementation of the time‐domain equation could become increasingly complicated when different modes of motion are coupled. This research presents a systematic introduction on how to implement the time‐domain analysis for floating structures, including the parameter transformations from the frequency domain to the time domain, and the methods for calculating and approximating the impulse functions and the fluid‐memory effects, with special attention being paid to the coupling terms among the different motion modes, and the correctness of the time‐domain‐equation implementation. The main purpose of this article is to provide relevant information for those who wish to build their own time‐domain analyses with the open‐source hydrodynamic analysis packages, although commercial packages are available for time‐domain analyses.

Current panel methods for wave-structure interactions employ the potential flow theory, which provide fast, reliable and relatively accurate predictions for the marine structures, and now some open source packages, NEMOH and HAMS, are available. In this research, the relative utility and performance of NEMOH and HAMS is compared with the well-known, state-of-art software, WAMIT. To bring focus to these comparisons, this research is based on three different floating structures: the truncated cylinder; the truncated cylinder with heave plate; and a novel multi-axis TALOS wave energy converter. To make the comparison more useful, this research investigates the incomplete and overlapped panels for the simple cylinder, to examine whether the respective code can handle these and still provide a meaningful solution. The comparisons may help us to understand whether the incomplete and/or overlapped panels can be used for simplifying the numerical modelling of those very complicated marine structures. From the comparisons, it can be seen the open source software, NEMOH and HAMS, both could produce very good results for the simple single marine structure, but also exhibit different capacities in dealing with more complicated marine structures. Specifically, HAMS could handle the thin structures and the overlapped panels effectively as WAMIT.