Journal ArticleDOI
The evolution of Tollmien-Schlichting waves near a leading edge. II - Numerical determination of amplitudes
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TLDR
In this article, a numerical solution of the unsteady boundary-layer equation is used to relate the amplitude of the asymptotic eigensolution, and consequently of the Tollmien-Schlichting wave, to that of the imposed free-stream disturbance for the special case of a uniformly pulsating stream.Abstract:
In the first part of this investigation, Goldstein (1983) has shown that the amplitude of the spatially growing Tollmien-Schlichting wave generated by a time-harmonic free-stream disturbance is related to the coefficient multiplying the lowest-order asymptotic eigensolution of the unsteady boundary-layer equation. In the present study, a numerical solution of the unsteady boundary-layer equation is used to relate the amplitude of the asymptotic eigensolution, and consequently of the Tollmien-Schlichting wave, to that of the imposed free-stream disturbance for the special case of a uniformly pulsating stream. It is pointed out that the ideas of this study can be extended to other, more complex bodies and free-stream oscillations.read more
Citations
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Journal ArticleDOI
Boundary-layer receptivity to freestream disturbances
TL;DR: The boundary-layer receptivity to external acoustic and vortical disturbances is reviewed in this article. But, the authors do not consider the effects of external acoustic or vortic disturbances on the boundary layer.
Journal ArticleDOI
Transition and Stability of High-Speed Boundary Layers
TL;DR: In this article, stability and laminar-turbulent transition in high-speed boundary-layer flows are discussed, emphasizing qualitative features of the disturbance spectrum leading to new mechanisms of receptivity and instability.
Journal ArticleDOI
Scattering of acoustic waves into Tollmien-Schlichting waves by small streamwise variations in surface geometry
TL;DR: By using the triple-deck scaling of Stewartson (1969) and Messiter (1970) it was shown that small but relatively sudden surface geometry variations that produce only very weak static pressure variations can nevertheless produce strong coupling between an externally imposed acoustic disturbance and a spatially growing Tollmien-Schlichting wave as discussed by the authors.
Journal ArticleDOI
Adjoint systems and their role in the receptivity problem for boundary layers
TL;DR: In this article, the effect of various sources on convective instabilities in a boundary layer is found by using the solution of an inhomogeneous adjoint problem, and the results are compared with the asymptotic solutions obtained from triple-deck theory, and agree with previous finite-Reynolds-number calculations.
Journal ArticleDOI
Stability and receptivity characteristics of a laminar separation bubble on an aerofoil
TL;DR: In this paper, the authors investigated the aerofoil wake behind an NACA-0012 aerodynamic model and found that the wake exhibits a laminar separation bubble and no absolute instability in the classical sense.
References
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Journal ArticleDOI
The unsteady laminar boundary layer on a semi-infinite flat plate due to small fluctuations in the magnitude of the free-stream velocity
R. C. Ackerberg,J. H. Phillips +1 more
TL;DR: Asymptotic and numerical solutions of the unsteady boundary-layer equations are obtained for a main stream velocity given by equation (1.1) in this article, which is attributed to exponentially small oscillatory eigenfunctions, which account for different initial conditions upstream.
Journal ArticleDOI
The generation of a Tollmien-Schlichting wave by a sound wave
TL;DR: In this paper, a spectral numerical method is used to study the two-dimensional unsteady flow over a flat plate in the presence of a plane sound wave propagating parallel to the flow.
Journal ArticleDOI
On the propagation of disturbances in a laminar boundary layer. I
S. N. Brown,K. Stewartson +1 more
TL;DR: In this article, an analysis of the response of a laminar boundary layer to a perturbation, either in the mainstream, or of the boundary conditions at the wall, is made.