A trimaran hull may suffer large amplitude motions such as heave and pitch in head waves when navigating with high speed, which will lead to seasickness and uncomfortable for the crew. The anti-motion appendage T-foil has a positive effect on reducing vertical motions of the trimaran in head waves. In this study, the key object is to introduce a hydrodynamic coefficient method based on fully nonlinear unsteady RANS method for calculating the vertical motions of the trimaran equipped with T-foil in regular head waves. Firstly, the details of the numerical simulation methods used in this study were briefly introduced. Secondly, the numerical method was validated and verified by grid convergence study and comparison with the experimental results. Then, numerical simulations were carried out to predict the vertical motions of the trimaran sailing with various Froude numbers and hydrodynamic coefficients and vertical motions of the trimaran equipped with and without T-foil covering a range of regular head waves were estimated. Finally, both transfer functions of heave and pitch motions and hydrodynamic coefficients of the trimaran were recorded, and the anti-motion effect of the T-foil was investigated. The influence of viscosity, as well as the forward speed of the trimaran was analyzed. The results obtained from the systematic study demonstrated that the numerical results had a reasonable agreement with the experimental data. The numerical method introduced in this study could be another way to predict the vertical motions of the trimaran equipped with a T-foil and the anti-motion effect of the T-foil was remarkable.
Trimaran has shown excellent performance in hydrodynamic, which is consisted of a main hull and two side hulls (Davis and Holloway, 2007). Seakeeping performance is of vital importance to the vessel and the crew (Fang and Chan, 2007). Thus, ship motions and seakeeping performance in waves have attracted lots of researchers’ attention and in order to solve the motion problems of the trimaran, large amounts of efforts have been focused on developing experimental and numerical methods to predict ship motions during the past decades.
