Effect of Wall Suction on Coherent Structures in a Turbulent Boundary Layer

2005 ◽  
Vol 32 (3) ◽  
pp. 281-290
Author(s):  
O. M. Oyewola
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Coherent Structures ◽  
Wall Suction

Behaviour of Coherent Structures in a Turbulent Boundary Layer with Wall Suction

1987 ◽  
pp. 399-407 ◽  
Author(s):  
L. Fulachier ◽  
T. Benabid ◽  
F. Anselmet ◽  
R. A. Antonia ◽  
L. V. Krishnamoorthy
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Coherent Structures ◽  
Wall Suction

scholarly journals On the different contributions of coherent structures to the spectra of a turbulent round jet and a turbulent boundary layer

2001 ◽  
Vol 448 ◽  
pp. 367-385 ◽  
Author(s):  
T. B. NICKELS ◽  
IVAN MARUSIC
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Turbulent Flows ◽  
Coherent Structures ◽  
Isotropic Turbulence ◽  
Structural Models ◽  
Spectral Measurements ◽  
Round Jet ◽  
Good Account ◽  
Single Size

This paper examines and compares spectral measurements from a turbulent round jet and a turbulent boundary layer. The conjecture that is examined is that both flows consist of coherent structures immersed in a background of isotropic turbulence. In the case of the jet, a single size of coherent structure is considered, whereas in the boundary layer there are a range of sizes of geometrically similar structures. The conjecture is examined by comparing experimental measurements of spectra for the two flows with the spectra calculated using models based on simple vortex structures. The universality of the small scales is considered by comparing high-wavenumber experimental spectra. It is shown that these simple structural models give a good account of the turbulent flows.

scholarly journals Numerical Simulation of Coherent Structures in the Turbulent Boundary Layer under Different Stability Conditions

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1068
Author(s):  
Shujin Laima ◽  
Hehe Ren ◽  
Hui Li ◽  
Jinping Ou
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Correlation Coefficient ◽  
Wind Velocity ◽  
Coherent Structures ◽  
Stability Conditions ◽  
Velocity Spectrum ◽  
Turbulent Eddy ◽  
Stable Conditions ◽  
The Stability

Coherent structures in the turbulent boundary layer were investigated under different stability conditions. Qualitative analyses of the flow field, spatial correlation coefficient field and pre-multiplied wind velocity spectrum showed that the dominant turbulent eddy structure changed from small-scale motions to large- and very-large-scale motions and then to thermal plumes as the stability changed from strong stable to neutral and then to strong unstable. A quantitative analysis of the size characteristics of the three-dimensional turbulent eddy structure based on the spatial correlation coefficient field showed that under near-neutral stability, the streamwise, wall-normal and spanwise extents remained constant at approximately 0.3 δ , 0.1 δ and 0.2 δ ( δ , boundary layer height), respectively, while for other conditions, the extent in each direction varied in a log-linear manner with stability; only the spanwise extent under stable conditions was also independent of stability. The peak wavenumber of the pre-multiplied wind velocity spectrum moves towards small values from stable conditions to neutral condition and then to unstable conditions; thus, for the wind velocity spectrum, another form is needed that takes account the effects of the stability condition.

Effect of plate manipulators on coherent structures in a turbulent boundary layer

AIAA Journal ◽  
1990 ◽  
Vol 28 (11) ◽  
pp. 1877-1884 ◽  
Author(s):  
Candace E. Wark ◽  
Ahmed M. Naguib ◽  
Hassan M. Nagib
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Coherent Structures

Effects of wall suction on a 2D rough wall turbulent boundary layer

2019 ◽  
Vol 60 (3) ◽  
Author(s):  
L. Djenidi ◽  
Md. Kamruzzaman ◽  
L. Dostal
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Rough Wall ◽  
Wall Suction

Growth and breakdown of low-speed streaks leading to wall turbulence

2007 ◽  
Vol 586 ◽  
pp. 371-396 ◽  
Author(s):  
MASAHITO ASAI ◽  
YASUFUMI KONISHI ◽  
YUKI OIZUMI ◽  
MICHIO NISHIOKA
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Low Frequency ◽  
Wall Turbulence ◽  
Linear Stability Theory ◽  
Transition Flow ◽  
Wall Suction ◽  
Low Speed ◽  
Low Speed Streaks ◽  
Near Wall

Two-dimensional local wall suction is applied to a fully developed turbulent boundary layer such that near-wall turbulence structures are completely sucked out, but most of the turbulent vortices in the original outer layer can survive the suction and cause the resulting laminar flow to undergo re-transition. This enables us to observe and clarify the whole process by which the suction-surviving strong vortical motions give rise to near-wall low-speed streaks and eventually generate wall turbulence. Hot-wire and particle image velocimetry (PIV) measurements show that low-frequency velocity fluctuations, which are markedly suppressed near the wall by the local wall suction, soon start to grow downstream of the suction. The growth of low-frequency fluctuations is algebraic. This characterizes the streak growth caused by the suction-surviving turbulent vortices. The low-speed streaks obtain almost the same spanwise spacing as that of the original turbulent boundary layer without the suction even in the initial stage of the streak development. This indicates that the suction-surviving turbulent vortices are efficient in exciting the necessary ingredients for the wall turbulence, namely, low-speed streaks of the correct scale. After attaining near-saturation, the low-speed streaks soon undergo sinuous instability to lead to re-transition. Flow visualization shows that the streak instability and its subsequent breakdown occur at random in space and time in spite of the spanwise arrangement of streaks being almost periodic. Even under the high-intensity turbulence conditions, the sinuous instability amplifies disturbances of almost the same wavelength as predicted from the linear stability theory, though the actual growth is in the form of a wave packet with not more than two waves. It should be emphasized that the mean velocity develops the log-law profile as the streak breakdown proceeds. The transient growth and eventual breakdown of low-speed streaks are also discussed in connection with the critical condition for the wall-turbulence generation.

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