CIRES, University of Colorado and NOAA/Earth System Research Laboratory, DSRC, Mail Code R/PSD99, 325 Broadway, Boulder, Colorado 80305-3328, USA.
J Acoust Soc Am. 2010 Aug;128(2):600-10. doi: 10.1121/1.3458815.
Long-range correlations of noise fields in arbitrary inhomogeneous, moving or motionless fluids are studied in the ray approximation. Using the stationary phase method, two-point cross-correlation function of noise is shown to approximate the sum of the deterministic Green's functions describing sound propagation in opposite directions between the two points. Explicit relations between amplitudes of respective ray arrivals in the noise cross-correlation function and the Green's functions are obtained and verified against specific problems allowing an exact solution. Earlier results are extended by simultaneously accounting for sound absorption, arbitrary distribution of noise sources in a volume and on surfaces, and fluid inhomogeneity and motion. The information content of the noise cross-correlation function is discussed from the viewpoint of passive acoustic characterization of inhomogeneous flows.
任意非均匀、运动或静止流体中噪声场的长程相关性在射线近似下进行研究。利用定相法，证明了两点噪声互相关函数可近似为描述两点之间相反方向声传播的确定性格林函数的和。获得了噪声互相关函数中各射线到达幅度与格林函数之间的显式关系，并针对允许精确解的特定问题进行了验证。通过同时考虑声吸收、体积和表面上任意分布的噪声源以及流体非均匀性和运动，扩展了早期的结果。从非均匀流的被动声学特性的角度讨论了噪声互相关函数的信息量。
