Extreme wave events are generally taken into account in the design of offshore structures, to assure integrity and safety of the structure. To accurately predict extreme wave impact loading, a realistic modeling of all aspects involved is required. CFD simulations have recently shown more and more promising results in this field, however at present most of the industry still relies on detailed model testing for wave impact predictions. Especially when impacts due to steep (nearly) breaking waves are considered, accurate numerical modeling is challenging. The difficulty starts with a realistic numerical representation of the incoming breaking wave, which is essential for a realistic simulation but by no means easy to obtain.
This paper presents an approach towards obtaining deterministic breaking waves numerically, and applying these in offshore applications. The presented method allows to numerically replicate a critical extreme wave (impact) event, and therewith opens doors for CFD to a whole new field of applications. An extreme event that was measured during a wave basin test can be replicated numerically to run design variations, or a design wave defined from Met Ocean data can be reproduced to simulate its impact on a structure. The possibilities of the new approach can be optimized by implementing it in a CFD simulation tool that allows for dynamic mooring line simulation, such that mooring failures under the impact of an extreme wave event can be studied numerically.
Examples of how the proposed method can assist the industry in future extreme environment modeling are presented, and results are compared to model basin results for the impact of a (numerically replicated) extreme breaking wave on a flexible mono pile structure.