Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2024-12-28T06:27:26.705Z Has data issue: false hasContentIssue false

Large-scale instabilities of turbulent wakes

Published online by Cambridge University Press:  29 March 2006

W. C. Reynolds
Affiliation:
Department of Mechanical Engineering, Stanford University

Abstract

The equations describing the statistical features of small amplitude waves in a turbulent shear flow are derived from the Navier-Stokes equations. Closure is achieved through a postulated constitutive equation for the alteration of the statistical properties of the turbulence by the organized wave. The theory is applied in an examination of the stability of a hypothetical wake consisting of small-scale turbulence enclosed within a steady uncontorted superlayer. A set of superlayer jump conditions is derived from fundamental considerations, and these are of more general interest. For this hypothetical flow the analysis predicts largescale instabilities and superlayer contortions reminiscent of large-eddy structures observed in real flows. These instabilities therefore offer an explanation of the presence of large-scale organized motions in turbulent free shear flows.

Type
Research Article
Copyright
© 1972 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ffowcs Williams, J. E., Rosenblat, S. & Stuart, J. T. 1969 J. Fluid Mech. 39, 547.
Grant, H. L. 1958 J. Fluid Mech. 4, 149.
Hussain, A. K. M. F. & Reynolds, W. C. 1970a J. Fluid Mech. 41, 241.
Hussain, A. K. M. F. & Reynolds, W. C. 1970b Department of Mechanical Engineering, Stanford University Rep. FM-6.
Hussain, A. K. M. F. & Reynolds, W. C. 1972 J. Fluid Mech. 54, 241.
Kibens, V. 1968 The intermittent region of a turbulent boundary layer. Ph.D. dissertation, The Johns Hopkins University.
Kovasznay, L. S. G. 1967 Phys. Fluids, 10 (suppl. II), 25.
Kovasznay, L. S. G., Kibens, V. & Blackwelder, R. F. 1970 J. Fluid Mech. 41, 283.
Lin, C. C. 1955 Theory of Hydrodynamic Stability. Cambridge University Press.
Liu, J. T. C. 1971 Phys. Fluids, to appear.
Lumley, J. 1967a Phys. Fluids, 10, 1405.
Lumley, J. 1967b Fluid Mechanics of Internal Flow, p. 152.
Lumley, J. 1970 J. Fluid Mech. 41, 413.
Payne, F. R. & Lumley, J. L. 1967 Phys. Fluids, 10 (suppl. II), 164.
Reynolds, W. C. & Hussain, A. K. M. F. 1972 J. Fluid Mech. 54, 263.
Schlichting, H. 1968 Boundary Layer Theory. McGraw-Hill.
Townsend, A. A. 1956 The Structure of Turbulent Shear Flow. Cambridge University Press.
Townsend, A. A. 1966 J. Fluid Mech. 26, 689.