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Acoustic boundary conditions at an impedance lining in inviscid shear flow

Accepted version
Peer-reviewed

Repository DOI


Type

Article

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Authors

Khamis, Doran 
Brambley, Edward James 

Abstract

The accuracy of existing impedance boundary conditions is investigated, and new impedance boundary conditions are derived, for lined ducts with inviscid shear flow. The accuracy of the Ingard–Myers boundary condition is found to be poor. Matched asymptotic expansions are used to derive a boundary condition accurate to second order in the boundary layer thickness, which shows substantially increased accuracy for thin boundary layers when compared with both the Ingard–Myers boundary condition and its recent first-order correction. Closed-form approximate boundary conditions are also derived using a single Runge–Kutta step to solve an impedance Ricatti equation, leading to a boundary condition that performs reasonably even for thicker boundary layers. Surface modes and temporal stability are also investigated.</jats:p>

Description

Keywords

acoustics, aeroacoustics, boundary layers

Journal Title

Journal of Fluid Mechanics

Conference Name

Journal ISSN

0022-1120
1469-7645

Volume Title

796

Publisher

Cambridge University Press (CUP)
Sponsorship
EJB gratefully acknowledges support from a Royal Society University Research Fellowship, and from a college lectureship from Gonville & Caius College, Cambridge. D. Khamis was supported by an EPSRC grant.