Extreme ocean waves. Part I. The practical application of fully nonlinear wave modelling

Abstract

Abstract This paper concerns the description of large surface water waves in realistic ocean spectra and explains how fully nonlinear wave modelling can be applied in practical design calculations. In particular, the proposed methodology incorporates: (i) the transitory nature of individual waves or wave groups arising in a random or irregular sea involving a significant spread of wave energy across the frequency domain; (ii) the short-crestedness of waves arising due to the directionality of the underlying wave components; and (iii) the nonlinearity associated with the evolution of the largest waves. The procedures outlined build directly upon two advances in wave modelling, reported by Bateman et al. [1,2]. By combining these solutions with initial or starting conditions originating from statistical theory describing the most probable shape of a large linear wave, fully nonlinear descriptions of extreme waves in realistic sea states can be achieved. Furthermore, such calculations can be undertaken with relatively modest computational effort and are directly relevant to a wide range of design wave calculations.