Aerodynamic sound generation in thermoviscous fluids: A canonical problem revisited

Christopher L. Morfey; Sergey V. Sorokin; Matthew C.M. Wright

doi:10.1016/j.jsv.2022.117253

Aerodynamic sound generation in thermoviscous fluids: A canonical problem revisited

Christopher L. Morfey, Sergey V. Sorokin, Matthew C.M. Wright^*

^*Corresponding author for this work

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Abstract

Although the Lighthill–Curle acoustic analogy theory is formally exact, the presence of linear source terms related to viscous stresses and non-isentropic density changes makes it unsuitable for studying aerodynamic sound generation in low Reynolds number thermoviscous flows. Here we use an extension of the Ffowcs Williams and Hawkings formulation, with thermoviscous effects explicitly included, to find an analytical solution to the canonical problem of sound radiation from a circular cylinder immersed in a viscous heat-conducting fluid and rotating sinusoidally about its axis. Existing published solutions are compared and an earlier null result is explained. The new analysis reveals the dominant source of sound at low Mach numbers to be unsteady viscous dissipation rather than Reynolds-stress quadrupoles, unless the fluid parameter B=αc²/c_p is zero.

Original language	English
Article number	117253
Journal	Journal of Sound and Vibration
Volume	539
ISSN	0022-460X
DOIs	https://doi.org/10.1016/j.jsv.2022.117253
Publication status	Published - 24 Oct 2022

Bibliographical note

Funding Information:
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. The authors are grateful for the anonymous reviewers’ helpful comments.

Publisher Copyright:
© 2022

Keywords

Aeroacoustics theory
Green's functions
Low Reynolds number flows
Unsteady dissipation

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Open Access articleFinal published version, 897 KBLicence: CC BY 4.0

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title = "Aerodynamic sound generation in thermoviscous fluids: A canonical problem revisited",

abstract = "Although the Lighthill–Curle acoustic analogy theory is formally exact, the presence of linear source terms related to viscous stresses and non-isentropic density changes makes it unsuitable for studying aerodynamic sound generation in low Reynolds number thermoviscous flows. Here we use an extension of the Ffowcs Williams and Hawkings formulation, with thermoviscous effects explicitly included, to find an analytical solution to the canonical problem of sound radiation from a circular cylinder immersed in a viscous heat-conducting fluid and rotating sinusoidally about its axis. Existing published solutions are compared and an earlier null result is explained. The new analysis reveals the dominant source of sound at low Mach numbers to be unsteady viscous dissipation rather than Reynolds-stress quadrupoles, unless the fluid parameter B=αc2/cp is zero.",

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AU - Morfey, Christopher L.

AU - Sorokin, Sergey V.

AU - Wright, Matthew C.M.

N1 - Funding Information: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. The authors are grateful for the anonymous reviewers’ helpful comments. Publisher Copyright: © 2022

PY - 2022/10/24

Y1 - 2022/10/24

N2 - Although the Lighthill–Curle acoustic analogy theory is formally exact, the presence of linear source terms related to viscous stresses and non-isentropic density changes makes it unsuitable for studying aerodynamic sound generation in low Reynolds number thermoviscous flows. Here we use an extension of the Ffowcs Williams and Hawkings formulation, with thermoviscous effects explicitly included, to find an analytical solution to the canonical problem of sound radiation from a circular cylinder immersed in a viscous heat-conducting fluid and rotating sinusoidally about its axis. Existing published solutions are compared and an earlier null result is explained. The new analysis reveals the dominant source of sound at low Mach numbers to be unsteady viscous dissipation rather than Reynolds-stress quadrupoles, unless the fluid parameter B=αc2/cp is zero.

AB - Although the Lighthill–Curle acoustic analogy theory is formally exact, the presence of linear source terms related to viscous stresses and non-isentropic density changes makes it unsuitable for studying aerodynamic sound generation in low Reynolds number thermoviscous flows. Here we use an extension of the Ffowcs Williams and Hawkings formulation, with thermoviscous effects explicitly included, to find an analytical solution to the canonical problem of sound radiation from a circular cylinder immersed in a viscous heat-conducting fluid and rotating sinusoidally about its axis. Existing published solutions are compared and an earlier null result is explained. The new analysis reveals the dominant source of sound at low Mach numbers to be unsteady viscous dissipation rather than Reynolds-stress quadrupoles, unless the fluid parameter B=αc2/cp is zero.

KW - Aeroacoustics theory

KW - Green's functions

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KW - Unsteady dissipation

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DO - 10.1016/j.jsv.2022.117253

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JO - Journal of Sound and Vibration

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ER -

Aerodynamic sound generation in thermoviscous fluids: A canonical problem revisited

Abstract

Bibliographical note

Keywords

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