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Feedback Instability in a Boundary-Layer Flow Over Roughness

Part of: Hydrodynamic stability

Published online by Cambridge University Press:  21 December 2009

S. N. Timoshin
S. N. Timoshin
Affiliation:
Department of Mathematics, University College London, Gower Street, London WC1E 6BT
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Abstract

Linear stability of an incompressible triple-deck flow over a wall roughness is considered for disturbances of high frequency. The wall roughness consists of two relatively short obstacles placed far apart on an otherwise flat surface. It is shown that the flow is unstable to feedback or global mode disturbances. The feedback loop is formed by algebraically decaying disturbances propagating upstream and weakly growing Tollmien-Schlichting waves travelling downstream and as such represents an interaction between modes from continuous and discrete spectra of the corresponding parallel-flow problem. An example of growth rate calculation for a specific roughness is considered.

MSC classification

Secondary: 76E09: Stability and instability of nonparallel flows

Information

Type
Research Article
Information
Mathematika , Volume 52 , Issue 1-2 , December 2005 , pp. 161 - 168
Copyright
Copyright © University College London 2005

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