Numerical study on whipping response in irregular waves with asymmetric slamming for ultra large container ships

Abstract

The occurrence of asymmetric slamming in oblique waves poses a challenge for ultra-large container ships, resulting in torsional and horizontal bending whipping. In this study, a 3D nonlinear time-domain hydroelastic analysis method considering asymmetric slamming is used to simulate the torsional and horizontal bending whipping of a 20,000 TEU container ship in oblique irregular waves. The irregular incident waves are described by the ISSC spectrum. The characteristics of torsional moments and horizontal bending moments in oblique irregular waves are discussed in detail. The load time histories, frequency spectra, time-frequency spectrums, and significant values are analyzed and it is revealed that the high-frequency components of torsional moment and horizontal bending moment exhibit randomness due to the unpredictable occurrence of large wave height components in irregular waves, leading to slamming and whipping responses of ships. Furthermore, the effects of ship speed, heading angle, significant wave height, wave mean period on the whipping response are analyzed through a comprehensive set of numerical simulations, as well as the characteristics of the bending and torsional moment along the ship.