Reprint of: Mean flow boundary layer effects of hydrodynamic instability of impedance wall

S.W. Rienstra, M. Darau

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

5 Citations (Scopus)


The Ingard-Myers condition, modelling the effect of an impedance wall under a mean flow by assuming a vanishing boundary layer, is known to lead to an ill-posed problem in time-domain. By analysing the stability of a mean flow, uniform except for a linear boundary layer of thickness h, in the incompressible limit, we show that the flow is absolutely unstable for h smaller than a critical hc and convectively unstable or stable otherwise. This critical hc is by nature independent of wave length or frequency and is a property of liner and mean flow only. An analytical approximation of hc is given for a mass-spring-damper liner. For an aeronautically relevant example, hc is shown to be extremely small, which explains why this instability has never been observed in industrial practice. A systematically regularised boundary condition, to replace the Ingard-Myers condition, is proposed that retains the effects of a finite h, such that the stability of the approximate problem correctly follows the stability of the real problem.
Original languageEnglish
Title of host publicationIUTAM Symposium on Computational Aero-Acoustics for Aircraft Noise Prediction (Southampton, UK, March 29-31, 2010)
EditorsR.J. Astley, G. Gabard
Publication statusPublished - 2010

Publication series

NameProcedia IUTAM
ISSN (Print)2210-9838


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