Stabilisation of first-mode disturbances in compressible boundary-layer flows

A. P. Tunney, J. P. Denier

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

    Abstract

    The growth of inviscid, subsonic disturbances in an external, compressible boundary-layer flow is linked with the existence of generalised points of inflection in the base flow. An inviscid neutral mode can propagate at a wavespeed equal to the streamwise boundary-layer velocity at the generalised point of inflection, and this neutral mode is adjacent to unstable modes in wavenumber space. This is an extension of the classical Rayleigh inflection point theorem in the incompressible theory. A compressible, flat-plate boundary layer contains a single generalised point of inflection and hence is unstable in the inviscid limit. Under the influence of a favourable pressure gradient and a heated surface, the boundary-layer flow develops a velocity overshoot; the streamwise velocity exhibits a local maximum. This development also modifies the number and location of generalised points of inflection, and hence, the behaviour of inviscid disturbances. In this paper we summarise the linear stability properties of boundary layers with a velocity overshoot and focus on the case where the first-mode disturbance is neutralised.

    Original languageEnglish
    Title of host publicationProceedings of the 20th Australasian Fluid Mechanics Conference
    PublisherAustralasian Fluid Mechanics Society
    Number of pages4
    ISBN (Electronic)9781740523776
    Publication statusPublished - 2016
    EventAustralasian Fluid Mechanics Conference (20th : 2016) - Perth, Australia
    Duration: 5 Dec 20168 Dec 2016
    Conference number: 20th

    Conference

    ConferenceAustralasian Fluid Mechanics Conference (20th : 2016)
    Abbreviated title20th AFMC
    CountryAustralia
    CityPerth
    Period5/12/168/12/16

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