有限水深环境中声辐射预测的快速边界元法

A fast BEM approach for acoustic radiation prediction in shallow water environment

由于水底和水面的影响,结构在有限水深环境中的辐射声场与在自由空间中的辐射声场有很大区别。为了更高效准确地分析有限水深环境中大规模结构的辐射声场,文章构建一种快速边界元法(boundary element method,BEM)。采用宽频快速多极算法对计算过程进行加速处理,针对算法中最为耗时的M2L/F2H变换过程,通过建立判定准则将均匀层格林函数中的多阶虚源分为近场和远场,从而设计不同求解方案,极大减少M2L/F2H的变换次数,显著提高求解效率。数值算例验证了文章方法的准确性和高效性,并体现出该方法在浅海声学分析中的工程潜力。

The radiated sound field of a structure in shallow water environment is very different from that in free space due to the influence from the bottom and surface of the water.In order to analyze the radiated sound field of a large-scale structure in shallow water environment more efficiently and accurately,a fast boundary element method(BEM)is developed in this paper.The method adopts a wide-band fast multipole algorithm to accelerate the computation process.For the most time-consuming process of M2L/F2H transformation,the paper presents a criterion to classify the image sources in the uniform-layer Green’s function into the near field and far field,so as to apply different solution schemes to reduce the amount of M2L/F2H transformations and thus improve the solution efficiency.Numerical examples verify the accuracy and efficiency of the method,and also show its engineering potential in shallow sea acoustic analysis.