Advancing the safe use of the ocean through understanding ocean waves

Unraveling the nonlinear behavior of ocean waves

　

Industrial activities in the ocean, such as shipping, fishing, and the development of marine energy and resources, are significantly influenced by ocean waves. In pursuit of maritime safety, our ongoing research centers on ocean waves, with a primary focus on freak/rogue waves—exceptionally large waves that emerge suddenly in the ocean. Our objective is to elucidate the nonlinear physical processes underlying the formation of freak/rogue waves through theoretical, numerical, and experimental methodologies. The insights gained from this research in physical oceanography are then applied to ocean engineering studies, aiming to decipher the behavior of ships and offshore structures in wave conditions.

Research on the wave-structure interaction for maritime safety

　

The structural integrity of ships and offshore structures must be designed to withstand the maximum wave loads to ensure their safety. Understanding their motion and load response to large waves is crucial for this purpose. However, phenomena such as wave breaking, impact loads from slamming, and the resulting elastic vibrations of structures are complex and highly nonlinear. To unravel these challenging physical phenomena and apply such insights to the rational design of ships and offshore structures, we conduct research on stochastic prediction of extreme responses of ships and offshore structures in waves, as well as on hydroelastic responses of ships and offshore structures in large waves.

Exploration of novel tank experiment techniques

　

Experimenting with scaled models of ships and offshore structures in large tank test facilities is one of the most useful methods for understanding their hydrodynamic or seakeeping performance. Tank experiments remain essential, particularly in investigating physical phenomena that are challenging to model numerically. Tank facilities themselves have evolved to incorporate sophisticated functionalities. For instance, the National Maritime Research Institute has established the Actual Sea Model Basin, equipped with 382 wave makers around its periphery. In this wave basin, we have developed techniques for generating various wave environments and experimental techniques with ship models in such wave environments. Additionally, we have initiated efforts towards automating tank testing in the towing tank at the University of Tokyo (smart towing tank concept).

Message

In our quest to ensure the safe use of the ocean, we conduct research focusing on the ocean engineering problem associated with waves, using theoretical, numerical, and experimental approaches. Although the expected results are not always obtained, especially in experiments, you may find it stimulating to grapple with the underlying causes and unravel the physics behind such phenomena. Let us work on together to solve challenging ocean engineering problems!