基于移动脉动线段源格林函数的波浪中并行两船耦合运动数值研究

Investigation of Coupled Motions of Two Ships Sailing Parallelly in Waves Based on Translating-pulsating Line Source Green’s Function

在三维频域势流理论框架下,使用移动脉动源格林函数构建边界积分方程求解速度势,建立了波浪中并行两船耦合运动的计算模型。为避免数值不稳定,采用解析公式计算格林函数在水平线段上的积分(命名为移动脉动线段源格林函数),以此来求得积分方程中的影响系数。在此基础上,自主开发规则波中两船航行时运动响应的数值计算程序。通过对单船在波浪作用下摇荡运动的模拟,验证了该程序的可靠性。然后对处于不同纵向相对位置的护卫舰和补给舰在规则波中迎浪航行时的耦合运动进行计算和分析。计算结果显示,论文方法的数值结果与试验值吻合良好。与脉动源格林函数法和基于纯数值求积公式的移动脉动源法相比,精度更高且更为稳定。两船间的水动力干扰对其中排水量较小的船影响更为显著,但这种影响随着两船纵向相对距离的增大而减弱。

Within the framework of three-dimensional frequency-domain potential flow theory, the translatingpulsating source Green’s function is applied to construct the boundary integral equation(BIE), and a computational model is established for the coupled motions of two ships sailing parallelly in waves. In order to avoid numerical instability, influence coefficients in the BIE are evaluated based on an analytical formula of the Green’s function distributing on the horizontal line segment(named as translating-pulsating line source Green’s function), and a computer program is developed based on this method. The numerical algorithm is validated through the simulation of motions of a single ship. Coupled motion responses of a frigate and a supply ship sailing parallelly in waves with or without stagger are calculated and analyzed respectively.Numerical results show that the present method is of better accuracy and stability than the pulsating source Green’s function method and the translating-pulsating source Green’s function using numerical integration formula. Influence of hydrodynamic interaction on the smaller ship is found to be more noticeable, which becomes weak with the increase of the longitudinal distance between two ships.