浅海波导中目标散射的边界元方法

提出了一种计算三维散射体在声速剖面随深度变化、距离无关浅海波导中散射声场的数值方法波导边界元方法。当散射体不十分靠近波导界面因而边界多次散射可以忽略时,在边界元计算中可以用自由场格林函数近似波导格林函数。应用镜像法和球波函数加法定理推导了理想波导中球体散射声场的解析解,用来验证波导边界元方法的计算精度,证明该数值方法是准确的。对浅海波导中水下潜器散射声场数值模拟的结果表明,浅海波导海面、海底界面反射、声速剖面等对目标散射声场的幅值和方向性都有很大的影响。 

Boundary element method for target scattering in shallow water waveguide

The boundary element method is coupled with normal modes model for the acoustic scattering from three dimensional objects in range independent shallow water ocean environment with arbitrary sound-speed profile. Theory and numerical example show that the waveguide Green function can be approximated by free space Green function when target is not too close to the waveguide boundary and multi-scattering effects can be ignore. The image method and addition theorems for the spherical wave functions are used to deduce exact analytic solution for sphere scattering in ideal waveguide. This solution can be used as a benchmark solution to validate the present numerical method. Scattering field from submerged vehicles in shallow water waveguide is calculated. Numerical results show that the effects of boundary reflection and sound-speed profile to target scattering in shallow water waveguide are obvious.