Faculty of Physics, Moscow State University, Moscow, Russia.
J Acoust Soc Am. 2011 Apr;129(4):1760-72. doi: 10.1121/1.3557034.
Finite amplitude acoustic wave propagation through atmospheric turbulence is modeled using a Khokhlov-Zabolotskaya-Kuznetsov (KZK)-type equation. The equation accounts for the combined effects of nonlinearity, diffraction, absorption, and vectorial inhomogeneities of the medium. A numerical algorithm is developed which uses a shock capturing scheme to reduce the number of temporal grid points. The inhomogeneous medium is modeled using random Fourier modes technique. Propagation of N-waves through the medium produces regions of focusing and defocusing that is consistent with geometrical ray theory. However, differences up to ten wavelengths are observed in the locations of fist foci. Nonlinear effects are shown to enhance local focusing, increase the maximum peak pressure (up to 60%), and decrease the shock rise time (about 30 times). Although the peak pressure increases and the rise time decreases in focal regions, statistical analysis across the entire wavefront at a distance 120 wavelengths from the source indicates that turbulence: decreases the mean time-of-flight by 15% of a pulse duration, decreases the mean peak pressure by 6%, and increases the mean rise time by almost 100%. The peak pressure and the arrival time are primarily governed by large scale inhomogeneities, while the rise time is also sensitive to small scales.
有限振幅声波在大气湍流中的传播采用 Khokhlov-Zabolotskaya-Kuznetsov（KZK）型方程进行建模。该方程考虑了非线性、衍射、吸收和介质的矢量非均匀性的综合影响。开发了一种数值算法，该算法使用激波捕捉方案来减少时间网格点的数量。不均匀介质采用随机傅里叶模式技术建模。N 波在介质中的传播会产生聚焦和散焦区域，这与几何射线理论一致。然而，在第一焦点的位置上观察到了多达十个波长的差异。结果表明，非线性效应增强了局部聚焦，增加了最大峰值压力（高达 60%），并减少了冲击波上升时间（约 30 倍）。虽然在焦点区域峰值压力增加，上升时间减少，但在距离声源 120 个波长处的整个波前进行统计分析表明，湍流：将脉冲持续时间的平均飞行时间减少 15%，将平均峰值压力降低 6%，并将平均上升时间延长近 100%。峰值压力和到达时间主要由大尺度不均匀性决定，而上升时间也对小尺度敏感。
