斜壁结构的水动力收敛方法研究

在分析波浪中的船舶运动或者计算大型结构的水动力系数时，往往采用时域格林函数方法。时域格林函数的一个重要局限性在于它在计算具有倾斜壁面的水动力系数时，结果很容易发散。时域格林函数本身的奇异性以及高频振动特性显然是水动力发散的一个重要原因。但即使该奇异性通过增加粘性以及表面张力的方式使之消失，计算具有斜壁结构的水动力时，发散现象依然存在。因此，该文提出一种滤波方法，除去时域格林函数的高频部分，留下其低频部分，并定义滤波系数，从而使作用于斜壁结构上的水动力值收敛。通过文中结果与频域兴波格林函数法的比较来确定最优滤波系数。结果表明：最优滤波系数几乎与运动幅值无关，但会受到运动频率以及物面形状的影响。

Convergence Method for Hydrodynamic Force on Surface Structures with Oblique Boundaries

An important limitation of time-domain Green function is its divergence when analyzing ship motions in waves or computing the hydrodynamic coefficients of large flattering structures with prescribed motions. Singularity and highly oscillatory properties of time-domain Green function surely are an distinct reason for the divergence of hydrodynamic force on surface structures with oblique boundaries, but even this problem is solved by considering surface tension and fluid viscosity, the di-vergence still exists when analyzing ship motions in waves or computing the hydrodynamic coeffi-cients for large flattering structures. Thus this paper gives out a filtering scheme by removing the high-frequency part of time domain Green function and leaving low-frequency part and defines a filtering coefficient, which can make the hydrodynamic force on surface structures with oblique boundaries convergent. The results in this paper are compared with that by frequency domain Green function method to determine the optimum filtering coefficient. Results show that the optimum filter-ing coefficient nearly has nothing to do with motion amplitude but is influenced by the motion fre-quency and the shape of surface structures.