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Cross-correlation function of acoustic fields generated by random high-frequency sources
1CIRES, 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
The Journal of the Acoustical Society of America
|August 17, 2010
Summary
Noise correlations in fluids reveal sound propagation paths. The two-point cross-correlation function approximates Green's functions, enabling passive acoustic flow characterization.
Area of Science:
- Acoustics
- Fluid Dynamics
- Wave Propagation
Background:
- Understanding acoustic phenomena in fluids is crucial for various applications.
- Characterizing fluid properties using passive acoustic methods remains a challenge.
Purpose of the Study:
- To analyze long-range correlations of noise fields in arbitrary fluid flows.
- To develop methods for passive acoustic characterization of inhomogeneous flows.
Main Methods:
- Ray approximation for noise field analysis.
- Stationary phase method to derive the two-point cross-correlation function.
- Comparison with deterministic Green's functions for validation.
Main Results:
- The noise cross-correlation function approximates the sum of Green's functions for sound propagation in opposite directions.
- Explicit relations derived between noise correlation amplitudes and Green's functions.
- Method accounts for sound absorption, source distribution, and fluid motion.
Conclusions:
- The study provides a theoretical framework for using noise correlations to understand sound propagation in complex fluids.
- Noise cross-correlation functions offer valuable information for passive acoustic flow characterization.
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