Numerical analysis of pitch and rolling motions of trimaran in oblique waves.

The coupled motion of roll and pitch is noticeable when trimaran sails in oblique head waves, which will lead to negative influence on the safety and comfort of navigation. In this paper, the numerical simulation of the trimaran's motion in oblique waves was carried out by open source CFD tool OpenFOAM, and the computed motion response was analyzed to study the characteristics of the torsional rolling. The OpenFOAM-based hybrid method used in this paper was briefly introduced first, and the numerical method was validated and verified by both the grid convergence test and the comparison with experimental result. Both the amplitude and the time history of the computed motion are used for analysis, and the influence of wave steepness, wave heading and forward speed of trimaran on the characteristics of torsional rolling was investigated. The result shows that the large wave steepness and the low forward speed will lead to dangerous torsional rolling motion of trimaran in oblique waves, and the dangerous condition is mainly caused by nonlinear rolling motion; the motion state is more sensitive and changing obviously with other factors at large wave steepness wave conditions. [ABSTRACT FROM AUTHOR]