1 Copyright © 2011 by ASME Proceedings of the ASME 30th International Conference on Offshore Mechanics and Arctic Engineering OMAE2011 June 19-24, 2011, Rotterdam, the Netherlands OMAE2011- 50316 TIME DOMAIN COMPARISON WITH EXPERIMENTS FOR SHIP MOTIONS AND STRUCTURAL LOADS ON A CONTAINER SHIP IN ABNORMAL WAVES Suresh Rajendran Centre for Marine Technology and Engineering (CENTEC), Technical University of Lisbon Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal Nuno Fonseca Centre for Marine Technology and Engineering (CENTEC), Technical University of Lisbon Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal C. Guedes Soares Centre for Marine Technology and Engineering (CENTEC), Technical University of Lisbon Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal Günther F. Clauss Ocean Engineering Division Technical University of Berlin Germany Marco Klein Ocean Engineering Division Technical University of Berlin Germany ABSTRACT The paper presents experimental results from model tests with a containership advancing in abnormal wave conditions and comparisons with numerical simulations. A nonlinear time domain method based on strip theory is used for the calculation of vertical ship responses induced by abnormal waves. This code combines the linear diffraction and radiation forces with dominant nonlinear forces associated with vertical response arising from Froude-Krylov forces, hydrostatic forces and shipping of green water. The time domain simulations are compared directly with experimental records from tests with a model of a container ship in deterministic waves for a range of Froude numbers. Extreme sea conditions were replicated by the reproduction of realistic abnormal waves like the New Year Wave and abnormal wave from North Alwyn. Head sea condition is considered and the comparisons include the wave elevation, the vertical motions of the ship and the vertical bending moment at midship. 1 INTRODUCTION Several methods varying from linear strip theory (Salvesen et al. [1]) to completely nonlinear method (Beck et al. [2], Subramani et al. [3]) have been developed to predict the ship response in moderate to extreme sea conditions. Practical application of most of the fully nonlinear methods is limited due to numerical complexity and the time consumed for running the numerical code while dealing complex hydrodynamic problem. In order to overcome such complexity, methods have been developed that use the partial nonlinear approach which makes use of the simplification of linear theory for the radiation and diffraction effects, while trying to incorporate the most important nonlinear contributions. Several partial nonlinear methods have been developed where some nonlinearity is accounted for (Watanabe and Sawada [4], Xia and Wang [5]) and comparisons of their performance are available (Watanabe and Guedes Soares [6]). Proceedings of the ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering OMAE2011 June 19-24, 2011, Rotterdam, The Netherlands OMAE2011-50316