Higher eigenmodes in the Blasius boundary-layer stability problem

Using the Orr-Sommerfeld equation with the wavenumber as the eigenvalue, a search for higher eigenstates in the stability theory of the Blasius boundary layer has revealed the existence of a number of viscous states in addition to the long established fundamental state. The viscous states are discrete, belong to two series, and are all heavily damped in space. Within the limits of the investigation the number of viscous states existing in the layer increases as the Reynolds number and the angular frequency of the perturbation increase. It is suggested that the viscous eigenstates may be responsible for the excitation of some boundary-layer disturbances by disturbances in the free stream.

Download Full-text

Numerical Investigations of the Influence of Distributed Roughness on Blasius Boundary Layer Stability

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition ◽

10.2514/6.2011-563 ◽

2011 ◽

Cited By ~ 7

Author(s):

Christoph Brehm ◽

Tim Dackermann ◽

Felix Grygier ◽

Hermann Fasel

Keyword(s):

Boundary Layer ◽

Boundary Layer Stability ◽

Numerical Investigations ◽

Blasius Boundary Layer

Download Full-text

Effect of angle of attack on hypersonic boundary-layer stability

AIAA Journal ◽

10.2514/3.13527 ◽

1997 ◽

Vol 35 ◽

pp. 464-470 ◽

Cited By ~ 1

Author(s):

Glen P. Doggett ◽

Ndaona Chokani ◽

Stephen P. Wilkinson

Keyword(s):

Boundary Layer ◽

Angle Of Attack ◽

Boundary Layer Stability ◽

Hypersonic Boundary Layer

Download Full-text

Effects of Local Cooling on Hypersonic Boundary-Layer Stability

AIAA Scitech 2021 Forum ◽

10.2514/6.2021-0940 ◽

2021 ◽

Author(s):

Furkan Oz ◽

Kursat Kara

Keyword(s):

Boundary Layer ◽

Boundary Layer Stability ◽

Hypersonic Boundary Layer ◽

Local Cooling

Download Full-text

Acoustic receptivity and evolution of two-dimensional and oblique disturbances in a Blasius boundary layer

Journal of Fluid Mechanics ◽

10.1017/s0022112000003220 ◽

2001 ◽

Vol 432 ◽

pp. 69-90 ◽

Cited By ~ 32

Author(s):

RUDOLPH A. KING ◽

KENNETH S. BREUER

Keyword(s):

Boundary Layer ◽

Surface Roughness ◽

Acoustic Wave ◽

Three Dimensional ◽

Two Dimensional ◽

Surface Waviness ◽

S Wave ◽

Boundary Layer Instability ◽

Blasius Boundary Layer ◽

Tollmien Schlichting

An experimental investigation was conducted to examine acoustic receptivity and subsequent boundary-layer instability evolution for a Blasius boundary layer formed on a flat plate in the presence of two-dimensional and oblique (three-dimensional) surface waviness. The effect of the non-localized surface roughness geometry and acoustic wave amplitude on the receptivity process was explored. The surface roughness had a well-defined wavenumber spectrum with fundamental wavenumber kw. A planar downstream-travelling acoustic wave was created to temporally excite the flow near the resonance frequency of an unstable eigenmode corresponding to kts = kw. The range of acoustic forcing levels, ε, and roughness heights, Δh, examined resulted in a linear dependence of receptivity coefficients; however, the larger values of the forcing combination εΔh resulted in subsequent nonlinear development of the Tollmien–Schlichting (T–S) wave. This study provides the first experimental evidence of a marked increase in the receptivity coefficient with increasing obliqueness of the surface waviness in excellent agreement with theory. Detuning of the two-dimensional and oblique disturbances was investigated by varying the streamwise wall-roughness wavenumber αw and measuring the T–S response. For the configuration where laminar-to-turbulent breakdown occurred, the breakdown process was found to be dominated by energy at the fundamental and harmonic frequencies, indicative of K-type breakdown.

Download Full-text