Time Domain Analysis of Ship Motion in Waves Using Finite Element Method

J. Ocean Eng. Technol. 2009;23(1):16-23.

Nam Bo-Woo,Sung Hong-Gun,Hong Sa-Young

Maritime & Ocean Engineering Research Institute KORDI,Maritime & Ocean Engineering Research Institute KORDI,Maritime & Ocean Engineering Research Institute KORDI

유한요소법을 이용한 파랑 중 선박운동의 시간영역 해석기법 개발

남보우,성홍근,홍사영

한국해양연구원 해양시스템안전연구소,한국해양연구원 해양시스템안전연구소,한국해양연구원 해양시스템안전연구소

Keywords: Ship motion, Time domain, Finite element method, Forward-speed problem

핵심용어: 선박운동, 시간영역, 유한요소법, 전진속도문제

Abstract

The three-dimensional ship motion with forward speed was solved by a finite element method in the time domain. A boundary value problem was described in the frame of a fixed-body reference, and the problem was formulated according to Double-Body and Neumann-Kelvin linearizations. Laplace's equation with boundary conditions was solved by a classical finite element method based on the weak formulation. Chebyshev filtering was used to get rid of an unwanted saw-tooth wave and a wave damping zone was adopted to impose a numerical radiation condition. The time marching of the free surface was performed by the 4th order Adams-Bashforth-Moulton method. Wigley I and Wigely III models were considered for numerical validation. The hydrodynamic coefficients and wave exciting forces were validated by a comparison with experimental data and the numerical results of the Wigley I. The effects of the linearization are also discussed. The motion RAO was also checked with a Wigley III model through mono-chromatic and multi-chromatic regular waves.