Hostname: page-component-78c5997874-j824f Total loading time: 0 Render date: 2024-11-17T18:22:38.635Z Has data issue: false hasContentIssue false
  • English
  • Français

An experimental investigation of coherent substructures associated with turbulent spots in a laminar boundary layer

Published online by Cambridge University Press:  20 April 2006

Eric C. Itsweire  and
Charles W. Van Atta
Eric C. Itsweire
Affiliation:
Department of Applied Mechanics and Engineering Sciences, and Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093
Charles W. Van Atta
Affiliation:
Department of Applied Mechanics and Engineering Sciences, and Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093
Get access Rights & Permissions [Opens in a new window]

Abstract

Longitudinal and transverse components of the velocity were simultaneously measured for various vertical locations at 20 off-centreline positions in turbulent spots artificially generated in a zero-pressure-gradient laminar boundary layer. Global ensemble-averaged velocity diagrams and vertical vorticity contours were computed in similarity coordinates ξ = (x − x0)/(U∞(t−t0)) and ζ = z/(U∞(t−t0)) for different heights η = y/δ* above the plate. This global averaging technique inadequately describes the spot, which is not a single large vortex structure. A discriminative averaging technique was developed to construct a ‘statistically most-probable’ spot with sufficient resolution to include some of the largest substructures detected in visual studies. Four eddies were identified in vertical slices of the central region of the spot, while several rows appeared in the plan view. These features of the velocity and vorticity contours of the statistically most-probable spot exhibit similarities with structures observed in flow visualizations.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 148 , November 1984 , pp. 319 - 348
Copyright
© 1984 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

Antonia, R. A., Chambers, A. J., Sokolov, M. & Van Atta, C. W. 1981 Simultaneous temperature and velocity measurements in the plane of symmetry of a transitional turbulent spot. J. Fluid Mech. 108, 317–393.Google Scholar
Cantwell, B. J., Coles, D. & Dimotakis, P. 1978 Structure and entrainment in the plane of symmetry of a turbulent spot. J. Fluid Mech. 87, 641–672.Google Scholar
Coles, D. & Barker, S. 1975 Some remarks on a synthetic turbulent boundary layer. In Turbulent Mixing in Nonreactive and Reactive Flows (ed. S. M. B. Murthy). Plenum.
Emmons, H. W. 1951 The laminar—turbulent transition in a boundary layer. Part I. J. Aero. Sci. 18, 490.Google Scholar
Gad-El-Hak, M., Blackwelder, R. F. & Riley, J. J. 1981 On the growth of turbulent regions in laminar boundary layers. J. Fluid Mech. 110, 73–96.Google Scholar
Head, M. R. & Bandyopadhyay, P. 1981 New aspects of turbulent boundary-layer structure. J. Fluid Mech. 107, 297–338.Google Scholar
Itsweire, E. C. 1983 An investigation of the coherent structures associated with a turbulent spot in a laminar boundary layer. Ph.D. thesis, University of California, San Diego.
Itsweire, E. C. & Van Atta, C. W. 1983 The effect of different similarity growth transformations on ensemble mean particle paths in turbulent spots. J. de Phys. Lett. 44, 917–923.Google Scholar
Leonard, A. 1980 Vortex simulation of three-dimensional spotlike disturbances in a laminar boundary layer. In Turbulent Shear Flows II (ed. L. J. S. Bradbury et al.), pp. 67–77. Springer.
Leonard, A. 1981 Turbulent structures in wall-bounded shear flow observed via three-dimensional numerical simulations. In The Role of Coherent Structures in Modelling Turbulence and Mixing (ed. J. Jimenez). Lecture Notes in Physics, vol. 136, pp. 119–145. Springer.
Matsui, T. 1980 Visualization of turbulent spots in the boundary layer along a flat plate in a water flow. In Proc. IUTAM Symp. on Laminar—Turbulent Transition, Stuttgart (ed. R. Eppler & H. Fasel), pp. 288–296. Springer.
Mautner, T. S. 1983 Investigation of the wall pressure, wall shear stress and velocity fields associated with a turbulent spot in a laminar boundary layer. Ph.D. thesis, University of California, San Diego.
Mautner, T. S. & Van Atta, C. W. 1982 An experimental study of the wall-pressure field associated with a turbulent spot in a laminar boundary layer. J. Fluid Mech. 118, 59–77.Google Scholar
Perry, A. E. & Chong, M. S. 1982 On the mechanism of wall turbulence. J. Fluid Mech. 119, 173–217.Google Scholar
Perry, A. E., Lim, T. T. & Teh, E. W. 1981 A visual study of turbulent spots. J. Fluid Mech. 104, 387–405.Google Scholar
Schlichting, H. 1956 Boundary Layer Theory. McGraw-Hill.
Schubauer, G. B. & Klebanoff, P. S. 1956 Contributions on the mechanisms of boundary layer transition. NACA Rep. 1289.Google Scholar
Van Atta, C. W. & Helland, K. N. 1980 Exploratory temperature-tagging measurements of turbulent spots in a heated laminar boundary layer. J. Fluid Mech. 100, 243–255.Google Scholar
Wygnanski, I. 1981a The effect of Reynolds number and pressure gradient on the transitional spot in a laminar boundary layer. In The Role of Coherent Structures in Modelling Turbulence and Mixing (ed. J. Jimenez). Lecture Notes in Physics, vol. 136, pp. 304–332. Springer.
Wygnanski, I. 1981b On turbulent spots. In Proc. 7th Symp. on Turbulence, University of Missouri—Rolla, Sept. 1981 (ed. Patterson & Zakin), pp. 390–400.
Wygnanski, I., Haritonidis, J. & Kaplan, R. E. 1979 On a Tollmien—Schlichting wave packet produced by a turbulent spot. J. Fluid Mech. 92, 505–528.Google Scholar
Wygnanski, I., Sokolov, M. & Friedman, D. 1976 On the turbulent ‘spot’ in a laminar boundary layer. J. Fluid Mech. 78, 785–819.Google Scholar
Wygnanski, I., Zilberman, M. & Haritonidis, J. H. 1982 On the spreading of a turbulent spot in the absence of a pressure gradient. J. Fluid Mech. 123, 69–90.Google Scholar
Zilberman, M. 1981 On the interaction of transitional spots and generation of a synthetic turbulent boundary layer. Ph.D. thesis, Tel-Aviv University.