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Computation of 3D-wave packet characteristics in an unstable boundarysubsonic layer

Delfs, J. (1997) Computation of 3D-wave packet characteristics in an unstable boundarysubsonic layer. EUROMECH 3rd European Fluid Mechanics Conference 1997, 15.-18. Sept. 1997 in Goettingen.

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Abstract

Realistic perturbations of technical flows are usually of limited spatio-temporal extent (e.g. gusts in the freestream, roughness elements, active control devices etc.). Early results for three-dimensional wave packets in incompressible flow were obtained in (1). Here, the time asymptotic response of the subsonic adiabatic flat plate boundary layer flow upon a pulsewise and localized perturbation is studied theoretically at supercritical Reynolds number using the saddlepoint technique as in (2). The analysis is based on linear theory and is local, i.e. parallel flow is assumed. An unstable disturbance wave packet moves as a whole and spreads out at the same time. Thus, the moving packet defines a set of velocities (U, V) in the (x,y)-plane (x-streamwise, y-spanwiseI by which it's disturbance content is transported. Only an observer, assuming a velocity in this range will see a non- decaying energy density A. It's temporal evolution A (t) measured.

Document Type:Conference or Workshop Item (Paper)
Additional Information: LIDO-Berichtsjahr=1997,
Title:Computation of 3D-wave packet characteristics in an unstable boundarysubsonic layer
Authors:
AuthorsInstitution or Email of Authors
Delfs, J.UNSPECIFIED
Date:1997
Status:Published
Keywords:wave packet, boundary layer stability, compressible flow, group velocity, wave packet amplification
Event Title:EUROMECH 3rd European Fluid Mechanics Conference 1997, 15.-18. Sept. 1997 in Goettingen
HGF - Research field:UNSPECIFIED
HGF - Program:Aeronautics
HGF - Program Themes:other
DLR - Research area:UNSPECIFIED
DLR - Program:L ST - Starrflüglertechnologien
DLR - Research theme (Project):L - Concepts & Integration
Location: Köln-Porz , Braunschweig , Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Institut für Entwurfsaerodynamik
Deposited By: elib DLR-Beauftragter
Deposited On:03 Apr 2006
Last Modified:27 Apr 2009 10:06

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