A time domain boundary element method for wave added resistance of ships taking into account viscous effects
A time domain boundary element method for wave added resistance of ships taking into account viscous effects
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DOI：
10.1016/j.oceaneng.2018.05.010
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发表时间：
2018-08
影响因子：
5
通讯作者：
M. Riesner;O. E. Moctar
中科院分区：
文献类型：
--
作者：
M. Riesner;O. E. Moctar
线性边界元法一般能提供足够精确的船舶在小振幅波浪中运动的预报。然而，当研究波浪引起的附加阻力时，非线性效应将被考虑。高阶效应，如二阶波浪诱导漂移力，在很大程度上取决于船舶前进速度。本文提出一种非线性时域朗肯源法，计算船舶在规则首波中以恒定航速前进时的波浪附加阻力。计算了全非线性定常流场。非线性弗劳德-克雷洛夫和静水压力通过对瞬时湿表面（未受干扰的入射波）上的压力积分得到。辐射力在时域中使用卷积积分（康明斯方法）计算;绕射力使用入射波绕射的线性耐波性问题产生的复力振幅计算。考虑了由湿表面变化引起的辐射和绕射效应。介绍了一种计算粘性波附加阻力的经验方法。对一艘14, 000 TEU集装箱船和一艘超大型油轮的数值计算结果与频域方法、CFD计算结果和实验拖曳水池测量结果进行了比较。
Linear boundary element methods generally provide accurately enough predictions of ship motions in small amplitude waves. However, when the wave-induced added resistance is investigated, nonlinear effects are to be accounted for. Higher order effects, such as second order wave-induced drift forces, depend largely on ships forward speed. This article presents a nonlinear time-domain Rankine source method to calculate the wave-induced added resistance of ships advancing at constant forward speed in regular head waves. The fully nonlinear steady flow was computed. Nonlinear Froude-Krylov and hydrostatic forces were obtained by integrating pressures over the instantaneous wetted surface (undisturbed incident wave). Radiation forces were computed in time domain using convolution integrals (Cummins approach); diffraction forces, were computed using the complex force amplitude resulting from the linear seakeeping problem of incident wave diffraction. Radiation and diffraction effects caused by the changing wetted surface were accounted for. An empirical approach to account for the viscous wave added resistance was introduced. Numerical results for a 14,000TEU container ship and a very large tanker were compared to results from a frequency domain method, CFD calculations, and experimental towing tank measurements.