Acoustic scattering cross section predicted from an accurate model of the spectrum of temperature fluctuations
作者:
R. J. Hill,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1979)
卷期:
Volume 65,
issue 6
页码: 1397-1401
ISSN:0001-4966
年代: 1979
DOI:10.1121/1.382925
出版商: Acoustical Society of America
数据来源: AIP
摘要:
Recent theoretical and experimental advances have produced an accurate model of the power spectrum of temperature fluctuations in turbulent air. This model temperature spectrum and a semiempirical energy spectrum are used to predict the shape of the acoustic scattering cross section as a function of wavenumber and scattering angle. Experiments have shown that the temperature spectrum in air has a ’’bump’’ at high wavenumbers, and the model temperature spectrum shows that this feature is expected theoretically. A corresponding bump is predicted to appear in the acoustic scattering cross section. The bump in the cross section is reduced if velocity fluctuations dominate the scattering, because the energy spectrum has no bump. For typical energy dissipation rates in the atmospheric boundary layer, a 2‐kHz acoustic sounder senses scattering attributable to the bump in the cross section. The amount of scattering attributable to the bump depends on the acoustic wavenumber and the microscale, and can be as much as 50% greater than the scattering predicted by the usual theoretical interpretation.
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