Long-term analysis of wave-induced loads using High Order Spectral Method and direct sampling of extreme wave events

Abstract

An approach for running long-term analysis of the wave environment and associated wave-induced structural loads, which includes effects of nonlinearity, irregularity and short crestedness of ocean waves is presented. The suggested approach combines a novel event-sampling technique with the efficient nonlinear wave solver High Order Spectral Method (HOSM) to represent the long-term wave environment by a large, yet computationally feasible, number of short-crested wave events which are simulated in HOSM. For the present study, HOSM is enhanced with a wave-breaking model, which improves the description of steep sea states in which wave breaking plays a role.Extensive validation of HOSM and the implemented wave-breaking model is carried out through comparison with model-test results for wave-crest statistics in long- and short-crested sea states and through direct comparison with CFD simulations.The proposed methodology is demonstrated on a case study considering a 106 years long-term analysis of wave crests and wave-in-deck loads, using a simplified load model to estimate drag loads on a deck structure.