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A Numerical Experiment on the Role of Surface Shear Stress in the Generation of SoundThe sound generated due to a localized flow over an infinite flat surface is considered. It is known that the unsteady surface pressure, while appearing in a formal solution to the Lighthill equation, does not constitute a source of sound but rather represents the effect of image quadrupoles. The question of whether a similar surface shear stress term constitutes a true source of dipole sound is less settled. Some have boldly assumed it is a true source while others have argued that, like the surface pressure, it depends on the sound field (via an acoustic boundary layer) and is therefore not a true source. A numerical experiment based on the viscous, compressible Navier-Stokes equations was undertaken to investigate the issue. A small region of a wall was oscillated tangentially. The directly computed sound field was found to to agree with an acoustic analogy based calculation which regards the surface shear as an acoustically compact dipole source of sound.
Document ID
20020041921
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Shariff, Karim
(NASA Ames Research Center Moffett Field, CA United States)
Wang, Meng
(Stanford Univ. Stanford, CA United States)
Merriam, Marshal
Date Acquired
August 20, 2013
Publication Date
January 1, 1996
Subject Category
Acoustics
Meeting Information
Meeting: DFD96 Meeting of the American Physical Society
Location: Syracuse, NY
Country: United States
Start Date: November 24, 1996
End Date: November 26, 1996
Sponsors: American Physical Society
Funding Number(s)
PROJECT: RTOP 505-59-53
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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