Title

Acoustic Energy in Ducts: Further Observations

Abstract

The transmission of acoustic energy in uniform ducts carrying uniform flow is investigated with the purpose of clarifying two points of interest. The two commonly used definitions of acoustic “nergy” flux are shown to be related by a Legendre transformation of the Lagrangian density exactly as in deriving the Hamiltonian density in mechanics. In the acoustic case the total energy density and the Hamiltonian density are not the same which accounts for two different “energy” fluxes. When the duct has acoustically absorptive walls neither of the two flux expressions gives correct results. A re-evaluation of the basis of derivation of the energy density and energy flux provides forms which yield consistent results for soft walled ducts. © 1979.

Department(s)

Mechanical and Aerospace Engineering

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1979 Elsevier, All rights reserved.

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