Rogue waves. Impact on ships and offshore structures/Волны-убийцы. Воздействие на корабли и морские сооружения

Издание на английском языке Rogue waves have attracted considerable attention in academia, the shipping and offshore industries, and the media during the past two decades. These waves – also called freak, abnormal, or giant waves – are very steep and much larger than the surrounding waves. Several accidents involving ships and offshore structures have been reported due to such waves, and yet, as of today, rogue waves are not explicitly included in classification society rules and offshore standards. The occurrence of rogue waves presents the shipping and offshore industry with two important questions: should these waves be accounted for in design? If so, how best to account for them? This position paper summarizes our latest knowledge on rogue waves and their impacts on marine structures in general and ships in particular. We also focus on research projects in which DNV GL has participated and that relate to rogue waves and their impacts on marine structures. We hope that this summary, together with our own insights, provides further understanding on the rogue wave phenomenon. We also discuss how the state-of-the–art knowledge on rogue waves can be utilized to improve current design, as well as the planning and execution of marine operations. Finally, we propose future research activities that are needed to support the possible inclusion of rogue wave effects in ship and offshore structure design and operational procedures. The need for satisfactory warning criteria for rogue waves is emphasized. The significance of severe sea state conditions may grow in some ocean regions in the future due to global warming. Therefore, taking rogue waves into account in the design and operation of marine structures may become an important part of adaptation to climate change. Contents Executive summary Introduction DNV GL activities on rogue waves EC MaxWave project EC Network SEAMOCS EC EXTREME SEAS project JIP CresT/ShortCresT Theoretical background Linear description of waves Second-order description of waves Higher order description of waves Definition of rogue waves Field observations of rogue waves Generation mechanisms of rogue waves Spatial focusing Temporal focusing Nonlinear focusing Numerical and theoretical investigation of rogue waves Shape of the wave spectrum and occurrence of rogue waves Crossing sea states Shallow water effects Wave-current interactions Experimental investigations of rogue waves Statistical and spectral description of waves Probability of occurrence of rogue waves Warning criteria for extreme and rogue waves Impact of rogue waves on loads and responses Current design practice and Marine Operations Conclusions and recommendations References