Cross-correlation function of acoustic fields generated by random high-frequency sources.
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.
Godin
Oleg A
OA
CIRES, University of Colorado and NOAA/Earth System Research Laboratory, DSRC, Mail Code R/PSD99, 325 Broadway, Boulder, Colorado 80305-3328, USA. Oleg.Godin@noaa.gov
D000042:Absorption; D000162:Acoustics; D008962:Models, Theoretical; D009038:Motion; D009622:Noise; D011312:Pressure; D013016:Sound