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A study of hairpin vortices in a laminar boundary layer. Part 1. Hairpin vortices generated by a hemisphere protuberance

Published online by Cambridge University Press:  21 April 2006

M. S. Acarlar
Affiliation:
AT&T Bell Laboratories, Allentown, PA 18015, USA
C. R. Smith
Affiliation:
Dept. of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015, USA

Abstract

It has been suggested that hairpin vortices may play a key role in developing and sustaining the turbulence process in the near-wall region of turbulent boundary layers. To examine this suggestion, a study was done of the hairpin vortices generated by the interaction of a hemisphere protuberancee within a developing laminar boundary layer. Under the proper conditions, hairpin vortices are shed extremely periodically, which allows detailed examination of their behaviour. Shedding characteristics of the hemispheres were determined using hot-film-anemometry techniques. The flow patterns created by the presence of the hairpin vortices have been documented using flow visualization and hot-film-anemometry techniques, and cross-compared with the patterns observed in the near-wall of a fully turbulent boundary layer. In general, it has been observed that many of the visual patterns observed in the near-wall region of a turbulent boundary layer can also be observed in the wake of the hairpin-shedding hemisphere, which appears supportive of the importance of hairpin vortices in the near-wall turbulence production process. Furthermore, velocity measurements indicate the presence of strong inflexional profiles just downstream of the hairpin-vortex generation region which evolve into fuller profiles with downstream distance, eventually developing a remarkable similarity to a turbulent-boundary-layer velocity profile.

Type
Research Article
Copyright
© 1987 Cambridge University Press

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References

Acarlar, M. S. & Smith, C. R. 1984 An experimental study of hairpin-type vortices as a potential flow structure of turbulent boundary layers. AFOSR Rep. FM-5, Dept. of Mech. Engrg. and Mech., Lehigh University, Bethlehem, PA.Google Scholar
Acarlar, M. S. & Smith, C. R. 1987 A study of hairpin vortices in a laminar boundary layer. Part 2. Hairpin vortices generated by fluid injection. J. Fluid Mech. 175, 4383.Google Scholar
Achenbach, E. 1974 Vortex shedding from spheres. J. Fluid Mech. 62, 209221.Google Scholar
Bogard, D. G. 1982 Investigation of burst structures in turbulent channel flows through simultaneous flow visualization and velocity measurements. Ph.D. dissertation. Dept. of Mechanical Engineering, Purdue University.
Coring, E. R. & Brodkey, R. S. 1969 A visual investigation of the wall region in turbulent flow. J. Fluid Mech. 37, 130.Google Scholar
Dryden, H. L. 1953 Review of the published data on the effects of roughness on transition from laminar to turbulent flow. J. Aero. Sci. 20, 47782.Google Scholar
Falco, R. E. 1981 Structural aspects of turbulence in boundary layer flows. Proc. 6th Biennial Symp. on Turbulence (ed. G. K. Patterson & J. L. Zakin). Dept. of Chem. Engng, University of Missouri, Rolla.
Hall, G. R. 1967 Interaction of the wake from bluff bodies with an initially laminar boundary layer. AIAA J. 5, 138692.Google Scholar
Head, M. R. & Bandyopadyay, P. 1981 New aspect of turbulent boundary-layer structure. J. Fluid Mech. 107, 297337.Google Scholar
Klebanoff, P. S. 1955 Measurements of the effect of two-dimensional roughness elements on boundary layer transition, J. Aeron. Sci., November, pp. 803–804.Google Scholar
Klebanoff, P. S., Tidstrom, K. D. & Sargent, L. M. 1962 The three-dimensional nature of boundary-layer stability. J. Fluid Mech. 12, 134.Google Scholar
Kline, S. J., Reynolds, W. C., Schroub, F. A. & Runstadler, P. W. 1967 The structure of turbulent boundary layers. J. Fluid Mech. 30, 741.Google Scholar
Maxworthy, T. 1972 The structure and stability of vortex rings. J. Fluid Mech. 51, 1532.Google Scholar
Metzler, S. P. 1982 Processes in the wall region of a turbulent boundary layer. M.S. thesis, Dept. of Mech. Engng. and Mech., Lehigh University.
Mochizuki, M. 1961a, Smoke observation on boundary layer transition caused by a spherical roughness element. J. Phys. Soc. Japan. 16, 9951008.
Mochizuki, M. 1961b Hot-wire investigations of smoke patterns caused by a spherical roughness element. Nat. Sci. Rep., Ochanomizu University, vol. 12, no. 2, pp. 87–101.Google Scholar
Möller, W. 1938 Experimentelle Untersunchung zur Hydromechanik der Kugel. Z. Phys. 39, 5780.Google Scholar
Mujumbar, A. S. & Douglas, W. J. M. 1970 Eddy shedding from a sphere in turbulent free streams. Intl J. Heat Mass Transfer 13, 16271629.Google Scholar
Offen, G. R. & Kline, S. J. 1973 Experiments on the velocity characteristics of ‘bursts’ and in the interactions between the inner and outer regions of a turbulent boundary layer. Rep. MD-31, Stanford University.
Perry, A. E. & Chong, M. S. 1982 On the mechanisms of wall turbulence. J. Fluid Mech. 119, 173217.Google Scholar
Perry, A. E., Lim, T. T. & Teh, E. W. 1981 A visual study of turbulent spots. J. Fluid Mech. 104, 387405.Google Scholar
Praturi, A. K. & Brodkey, R. S. 1978 A stereoscopic visual study of coherent structures in turbulent shear flow. J. Fluid Mech. 89, 25172.Google Scholar
Schraub, F. A., Kline, S. J., Henry, J., Runstadler, P. W. & Littel, A. 1965 Use of hydrogen bubbles for qualitative determination of time dependent velocity fields in low-speed water flows. Trans. ASME D: J. Basic Engng. 87, 429444.Google Scholar
Smith, C. R. 1978 Visualization of turbulent boundary layer structure using a moving hydrogen bubble wire probe. Lehigh Workshop on coherent Structure in Turbulent Boundary Layers (ed. C. R. Smith & D. E. Abbott, pp. 48–97.
Smith, C. R. 1984 A synthesized model of the near-wall behaviour in turbulent boundary layers. Proc. 8th Symp. on Turbulence. (ed. G. K. Patterson & J. L. Zakin). Dept of Chem. Engrg., University of Missouri, Rolla.
Taneda, S. 1956 Experimental investigation of the wake behind a sphere at low reynolds numbers. J. Phys. Soc. Japan. 11, 11041108.Google Scholar
Tani, I. 1961 Effect of two-dimensional and isolated roughness on laminar flow. In Boundary Layer and Flow Control, vol. 2, pp. 637–656. Pergamon.
Tani, I. 1981 Three-dimensional aspects of boundary-layer transition, Proc. Indian Acad. Sci. 4, 219238.Google Scholar
Torobin, L. B. & Gauvin, W. H. 1959 Fundamental aspects of solids-gas flow. Part II. The sphere wake in steady laminar fluids. Can. J. Chem. Engng 37, 167176.Google Scholar
Utami, T. & Ueno, T. 1979 Lagrangian and Eularian measurement of large scale turbulence by flow visualizing techniques. In Flow Visualization. (ed. T. Asanunra), p. 221. Hemisphere.
Wille, R. 1972 Generation of oscillatory flows. In Flow Induced Structural Vibrations (ed. E. Naudascher), pp. 1–16. Springer.