THE NEAR-SOUND FIELD OF TURBULENCE,

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 Lighthill's 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)

Document Details

Document Type
Technical Report
Publication Date
Oct 01, 1959
Accession Number
AD0630684

Entities

People

  • G. J. Franz

Tags

DTIC Thesaurus Topics

  • Boundaries
  • Boundary Layer
  • Directional
  • Fluid Mechanics
  • Frequency
  • Intensity
  • Layers
  • Particles
  • Radiation
  • Sound Pressure
  • Spectra
  • Turbulence
  • Turbulent Boundary Layer

Fields of Study

  • Physics

Readers

  • Atmospheric Science / Meteorology, specifically Wind Wave Turbulence.
  • Plasma Physics / Magnetohydrodynamics