Accession Number:

AD0630684

Title:

THE NEAR-SOUND FIELD OF TURBULENCE,

Descriptive Note:

Corporate Author:

DAVID TAYLOR MODEL BASIN WASHINGTON D C HYDROMECHANICS LAB

Personal Author(s):

Report Date:

1959-10-01

Pagination or Media Count:

41.0

Abstract:

General expressions for the velocity potential, particle velocity, instantaneous sound pressure, mean-square sound pressure, and sound intensity for the sound generated by turbulence are derived, starting from Lighthills fundamental relations for the density fluctuations in the medium outside a turbulent region. The dipole radiation from the turbulent boundary layer of a rigid boundary, the quadrupole radiation from isotropic turbulence, and the lateral quadrupole radiation from turbulence in the presence of a large mean shear are discussed. The frequency spectra and directional patterns of the sound observed at points in the sound field that are much less than a wavelength from multipole sound sources are shown to differ significantly from the frequency spectra and directional patterns of the sound observed at points in the sound field that are many wavelengths from the multipole sound sources. Author

Subject Categories:

  • Acoustics
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE