Numerical and Physical Modelling of Extreme Wave Impacts on a Fixed Truncated Circular Cylinder

With a history of international failures, the survival envelope for wave energy convertors (WECs) has become an important consideration in the design of such systems. Potential design solutions require a better understanding of the hydrodynamics and structural loading experienced during extreme events, like rogue wave impact. This paper concerns the numerical modelling and experimental validation of extreme rogue wave interactions with a fixed truncated circular cylinder. Typical extreme waves from the intermediate depth Wave Hub site were produced at 1:30 scale in the COAST Lab Ocean basin at Plymouth University from the 100 year wave statistics using the dispersive focussing method, NewWave. A fixed 0.4m diameter cylinder with a 0.4m draft was used to represent the geometry of a generic point-absorber type WEC. Physical conditions were duplicated in a numerical wave tank, solving the fully nonlinear Navier-Stokes equations, with a free surface, using the volume of fluid (VoF) method and open source CFD library OpenFOAM®. The comparison between the results shows that the CFD software is capable of simulating extreme wave interactions with a fixed cylinder and the associated hydrodynamic phenomena very well. Keywords— Wave Energy Converter (WEC), survivability, NewWave, OpenFOAM®, waves2Foam, VoF method

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