A Three-Step Hybrid Method to Study the Influence of Green Water Impact on a Large Containership in Time Domain

Abstract

The paper introduces a simplified coupled computational fluid dynamics–boundary element method–finite element method (CFD–BEM–FEM)-based approach to study the effect green water induced loading on global structural responses such as bending moment and shear force. The proposed numerical scheme is based on a coupled three-step model. Initially, rigid modes of structural motions are calculated adopting a three-dimensional (3D) time domain panel method without incorporating the green water loading. The time histories of the green water impact on the deck are computed using a finite volume-based CFD tool with these precalculated rigid body motions. Finally, the problem of fluid–structure interaction is solved by considering the green water force as an external input. The direct integration scheme (i.e., Newmark–Beta method in the time domain) is employed to solve this structural problem modeled with one-dimensional FEM. To check the robustness and efficacy of the proposed model and to evaluate green water effect on the structure and vice versa, a large container vessel with and without forward speed is investigated. The impact is studied with respect to motion, shear force, and bending moment. The results confirm that the impact of green water and structural flexibility is significant. Therefore, these effects must be considered while designing a container ship. Also, from the results, it appears that the present three-step model is an effective, efficient, and useful practical tool to predict such effects.