修正一阶Born近似改进水中弱散射目标的散射声场预报

在推导Fourier衍射定理中运用一阶Born近似时忽略了弱散射体内外的波数差异,使散射声场方向特性的预报产生较大误差,针对这一问题,对一阶Born近似进行修正。考虑散射体内外波数差异引起的幅度和相位误差,通过调整频域采样圆弧半径并移动圆心位置得到了修正的一阶Born近似解。由于更准确地反映了目标与周围水介质的声学性质,有效提高了散射声场的预报精度。根据修正的Born近似计算了弱散射条件下无限长圆柱目标的散射远场指向性,结果与严格解相吻合,对其它形状截面的柱状目标也得到了合理的计算结果。 

Modification to first-order Born approximation for improved prediction of scattered sound from weakly scattering objects

When deriving the Fourier diffraction theorem based on the first-order Born approximation, the difference between wave number of the scattering object and that of the surrounding medium is ignored, causing substantial errors in sound scattering prediction. This paper modifies the Born approximation by taking into account the amplitude and phase changes at the interface between the scattering object and the water due to the wave number difference. By changing the radius and center position of the sampling circle in the Fourier domain, accuracy of the predicted sound scattering is improved. With the modified Born approximation, the computed far-field directional pattern of the scattered sound from a circular cylinder is in good agreement with the rigorous solution. Numerical calculations for several objects with different shapes are used to show applicability and effectiveness of the proposed method.