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Special Problems and Solutions for Numerical Prediction on Longitudinal Motion of Trimaran

For the numerical prediction on motion responses and performances of trimaran in regular wave, this paper solves two special problems for trimaran, which include abnormal numerical oscillation for the high frequency motion and obvious stem rising and stern falling due to large variation of navigation posture. On one hand, the authors introduced an artificial viscous force on the free surface between main and side sections to restrain the abnormal numerical oscillation. On the other hand, in order to consider the influence of navigation posture, the authors revised wet surface in motion prediction. Finally, some test cases were calculated and simulated to validate the present method. Compared with experimental data, the results of trimaran model with transom stern show that artificial viscous force has obvious effect on the heave response and small influence on the pitch motion. Furthermore, navigation posture plays a very important role on pitch and little action on heave movement. Especially, for trimaran model with low speed, viscous force and navigation posture basically have no effect on the results of motion prediction.