Wind-wave misalignment and a combination method for direction-dependent extreme incidents

The misalignment of wind and waves is of special interest for various engineering applications, i.e. for structural fatigue load analyses, for work vessel operations for offshore construction or maintenance, and for floating wind turbines. In addition to the normal or frequent boundary conditions, the combination of extreme loads and their directions is essential for coastal and offshore designs. These aspects are addressed by analyzing ten years of field measurements in the German Bight of the North Sea, which is intensively used for offshore wind energy production. This paper focuses on the occurrence and amount of wind and wave misalignment as well as the direction dependency of the wind-wave correlation for normal conditions and extreme storms. Subsequently, the influence of statistical distribution functions for the estimation of extreme wind and wave values is presented. Based on these results, a method is developed to combine direction dependent extreme wind and wave incidents for return periods of several decades.