Estimation of Vertical, Horizontal and Torsional Rigid Body Loads of an Ultra-Large Container Ship (ULCS) in Regular Waves

Abstract

Abstract Predicting hull responses and structural loads is essential for the robust design of ships. The Ultra Large Container Ships (ULCS) are subjected to non-linear wave loads due to the low block coefficient and pronounced bow flare. They are highly susceptible to torsional loads because of the large open cross-section which is subjected to unsymmetrical hydrodynamic loading. A time domain method based on strip theory is developed for estimating the coupled rigid body motions and wave-induced loads acting on an Ultra large containership. A 2D-Panel method is followed to calculate the added mass and damping coefficients. A body-nonlinear approach is followed to capture the major source of non-linearity in the structural load estimation due to Froude-Krylov and restoring forces. Case studies are conducted for an Ultra-large container ship in small amplitude regular waves. Motions and structural load (vertical, horizontal, and torsional load) RAOs are being investigated for various wave headings, and the results are compared with the published experimental results. The proposed method is computationally efficient to capture coupled rigid body responses and sectional loads, including torsion.