On the origin of streamwise vortices in a turbulent boundary layer

Several experiments have suggested that streamwise vortices, with their accompany-ing low-momentum streaks in a turbulent boundary layer have a characteristic spanwise wavelength of approximately λz+ = 100. Here a mechanism is proposed which selects a comparable spanwise wavelength and produces coun...

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Bibliographic Details
Published in:Journal of fluid mechanics 1986-08, Vol.169 (1), p.109-123
Main Authors: Jang, P. S., Benney, D. J., Gran, R. L.
Format: Article
Language:English
Subjects:
Exact sciences and technology
Fluid dynamics
Fundamental areas of phenomenology (including applications)
Physics
Turbulent flows, convection, and heat transfer
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Summary:Several experiments have suggested that streamwise vortices, with their accompany-ing low-momentum streaks in a turbulent boundary layer have a characteristic spanwise wavelength of approximately λz+ = 100. Here a mechanism is proposed which selects a comparable spanwise wavelength and produces counter-rotating streamwise vortices in a turbulent boundary layer. Examining the equations which describe the deviation of the velocity field from its time-average, it is found that a resonance (Benney & Gustavsson 1981), is associated with the mean-velocity profile. As an integral part of this resonance, there is a mean secondary flow which has a spanwise wavelength λz+ = 90 and whose velocities exhibit a streamwise vortex structure similar to those observed.
ISSN:0022-1120
1469-7645
DOI:10.1017/S0022112086000551