浮体在时域中的瞬时运动和波浪力数值模拟

Numerical simulation of the transient motion and wave exciting force for a floating body in the time domain

考虑浮体时域运动及波浪力计算中时域Green函数的计算困难,由时域Green函数及其导数表达式,建立各自满足的定常非齐次常微分方程.考虑常微分方程的定常、非齐次特性,引入精细时程方法进行数值计算;与此同时,给出了此方法中难以确定的定常系数矩阵的选取建议.同时由此方法计算所得时域Green函数应用于零航速浮体的瞬时运动和波浪力数值计算.研究结果表明,在相同时间步长(如Δt=0.01)时,此方法相对于四阶Runge-Kutta更为准确的计算了时域Green函数;为浮体在时域中的准确预报,提供了可靠的数值基础.

This research study is proposed considering the difficulties in calculation of the time domain Green function for floating body motions and the wave forces in time domain.As a result of the research paper,the findings established steady,non-homogeneous ordinary differential equations（ODEs） from time domain Green function and its derivatives,respectively satisfying the properties of Green function and its derivatives.The ODE is a steady,non-homogeneous system,utilizing the precise time-integration method（PIM） to help with solving the problem in numerical calculation.This paper also gives a suggestion on selection of the steady coefficient matrix that is usually confused in the method.Meanwhile,numerical calculation of the transient motions and wave exciting forces at zero forward speed is done based on time domain Green function derived from the method above.The results indicate that,with the same time step（such as Δt=0.01）,this method is much more accurate in calculating the time-domain Green function compared with the fourth-order Runge-Kutta method,which provides a reliable numerical basis for accurately predicting the floating body in the time domain.