The Prediction Of Roll Damping And Nonlinear Motion Of Trimaran

As a kind of high military value vessel, the trimaran with high sea-keeping performance is drawing more attentions. Some countries has carried out researches both in theory and by the mean of experiment. And during the past few years the U.S. Navy has adopted the trimaran as a choice in her LCS project.Since then 2.5D theory that developed by recent years introduce an efficient frequency domain method into numerical calculation of the sea-keeping performance of the trimaran. In this thesis, the Impulse Response Function theory that based on the 2.5D method is proposed to compute the large amplitude motion response characteristics of the high speed trimaran in both oblique regular waves and irregular waves. The Froude-Krylov force and hydrostatic restoring force are evaluated by integrating the pressure term over the instantaneous wetted surface. To estimate the Roll damping coefficient of the trimaran, two analytical methods including the crossflow approach and a numerical method by simulating free decay experiment that based on commercial CFD software are presented.