Further validation study of hybrid prediction method of parametric roll

Abstract

The International Maritime Organization (IMO) is developing Direct Stability Assessment (DSA) criteria for Parametric Roll (PR) and other four failure modes under the framework of second generation intact stability criteria, which will be very helpful for further enhancement of the safety level of ship design. According to previous studies, roll damping plays an important role in the simulation of PR, and a hybrid prediction method for ship parametric roll has been developed, which uses direct CFD approach to estimate roll damping coefficients, as well as weakly-nonlinear model to predict 3 D.O.F motion responses. The well-known container ship C11 was adopted for validation in the previous study, and comparison study has been conducted among hybrid method, a 1 D.O.F non-linear dynamics method and direct CFD prediction method for PR. The results show that the proposed hybrid method has reached sufficient accuracy, and can be used at early design stage of a ship. From the engineering point of view, more validations are necessary to further explore the robustness of the hybrid method, especially the specific applicable condition. In this research, further validation study of the hybrid method is done with three more ships, including two container ships and one Ro-Ro ship. Based on the comparison of results from numerical simulations and experiments, the prediction accuracy of the hybrid method is investigated and limitations are discussed. From this study one can obtain experience of time-domain numerical simulation, and make contributions to the development of IMO DSA criteria guideline.