Nonlinear Wave Group Impact on a Cylindrical Monopile

The ComFLOW wave model has been employed to study the impact of nonlinear wave groups on cylindrical monopiles. Four nonlinear wave groups are selected from fully nonlinear waves generated by a 2D ComFLOW model, representing wave groups with the largest or the second largest crest heights, the largest wave height and a wave group consisting of consecutive large waves. These four wave groups are used to investigate the wave loads on the foundation and the platform in a 3D ComFLOW model. Model results show that the maximum wave loads on the foundation and the platform by nonlinear wave groups are determined by their individual wave crest height. This study presents a relationship between platform level and wave impact on the platform, as the vertical force on the platform is the combination of buoyancy force (if inundated) and wave impact force due to wave run-up. Results also show that wave loads on the foundation and wave impact on the platform decrease as the wave period increases from 13s to 16s (typical wave period at German Bight). A wave group can cause a larger wave load on the foundation and the platform than regular waves, considering a regular wave height equal to the maximum wave height, regardless of the associated wave period (period of individual wave or peak period).