Numerical simulation of rolling for 3-D ship with forward speed and nonlinear damping analysis

• Published in: Journal of hydrodynamics. Series B 2013-02, Vol.25 (1), p.148-155
• Main Authors: YANG, Chun-lei, ZHU, Ren-chuan, MIAO, Guo-ping, FAN, Ju
• Format: Article
• Language: English
• Subjects: 3-D; Amplitudes; Damping; Engineering; Engineering Fluid Dynamics; Fittings; forced roll; free decay; Hydrology/Water Resources; Mathematical models; nonlinear damping; Nonlinearity; Numerical and Computational Physics; RANS method; Rolls; Ships; Simulation; Three dimensional; 前进速度; 数值模拟; 滚动预测; 船舶; 阻尼分析; 阻尼系数; 非线性特性
• ISSN: 1001-6058; 1878-0342
• DOI: 10.1016/S1001-6058(13)60348-0

Strongly nonlinear characteristics of ship roll owing to viscous effect can be usually observed. To describe the nonlinear roll behavior, the CFD method has been frequently employed with obvious advantages compared with the traditional semi-empirical formula method in estimating the roll damping. Numerical simulations of free decay and forced rolling at various forward speeds and amplitudes for a 3-D ship hull are conducted in the present research to predict ship roll damping, in which a RANS solver is employed and a dynamic mesh technique is adopted and discussed in detail. Numerical results, including nonlinear flow characters around ships, rolling decay curves and damping coefficients, show that they are all in good agreement with available experimental data. The linear and nonlinear damping coefficients are estimated and analyzed by fitting with exponential functions for various rolling amplitudes, frequencies and speeds in the free decay simulations, and the damping coefficients are obtained by a polynomial fitting in the forced roll simulations. It is indicated that the damping coefficients increase with increasing rolling angle amplitude and velocity. It is also emphasized that the effect of forward speed is significant to roll damping and the nonlinear damping decreases with increasing velocity.