Numerical study on wave-induced drift forces and motions of a DTC ship in head and oblique waves using functional decomposition model

Abstract

It is imperative to investigate the adequacy of propulsion power and steering mechanisms in order to maintain the manoeuvrability of ships in adverse wave conditions, as the drift forces caused by wave can result in deviation from the desired course. The primary objective of this research is to develop a hybrid approach, combining potential and viscous flows, known as SWENSE (Spectral Wave Explicit Navier-Stokes Equations), to accurately assess the wave-induced drift forces and motions experienced by ships in waves. SWENSE is a hybrid approach based on the functional decomposition model, in which the total field is composed of the incident field and complementary field. In this study, the incident filed waves are calculated by the Airy wave theory and the complementary field is solved by the SWENSE model. The wave conditions are selected according to the benchmark cases of the European Union research project SHOPERA (Energy Efficient Safe Ship Operation). The wave-induced loads and motions of DTC in head and oblique waves are calculated. Results of CFD (Computational Fluid Dynamics) are compared with those of EFD (Experimental Fluid Dynamics) and other numerical methods. In addition, the wave-induced drift forces of the fixed/3DOF (Degrees of Freedom) ships are compared with each other (3DOF includes heave, roll and pitch). SWENSE model is proven to be reliable for the predictions of the wave-induced drift forces and motions of ships in waves.