Hostname: page-component-5c6d5d7d68-vt8vv Total loading time: 0.001 Render date: 2024-09-01T10:57:26.489Z Has data issue: false hasContentIssue false
  • English
  • Français

On the generation of steady streamwise streaks in flat-plate boundary layers

Published online by Cambridge University Press:  30 March 2012

Jens H. M. Fransson  and
Alessandro Talamelli
Jens H. M. Fransson*
Affiliation:
Linné Flow Centre, KTH Mechanics, SE-10044 Stockholm, Sweden
Alessandro Talamelli
Affiliation:
Linné Flow Centre, KTH Mechanics, SE-10044 Stockholm, Sweden DIEM, Alma Mater Studiorum, Università di Bologna, I-47100 Forlì, Italy
*
†Email address for correspondence: jensf@mech.kth.se
Get access Rights & Permissions [Opens in a new window]

Abstract

A study on the generation and development of high-amplitude steady streamwise streaks in a flat-plate boundary layer is presented. High-amplitude streamwise streaks are naturally present in many bypass transition scenarios, where they play a fundamental role in the breakdown to turbulence process. On the other hand, recent experiments and numerical simulations have shown that stable laminar streamwise streaks of alternating low and high speed are also capable of stabilizing the growth of Tollmien–Schlichting waves as well as localized disturbances and to delay transition. The larger the streak amplitude is, for a prescribed spanwise periodicity of the streaks, the stronger is the stabilizing mechanism. Previous experiments have shown that streaks of amplitudes up to 12 % of the free stream velocity can be generated by means of cylindrical roughness elements. Here we explore the possibility of generating streaks of much larger amplitude by using a row of miniature vortex generators (MVGs) similar to those used in the past to delay or even prevent boundary layer separation. In particular, we present a boundary layer experiment where streak amplitudes exceeding 30 % have been produced without having any secondary instability acting on them. Furthermore, the associated drag with the streaky base flow is quantified, and it is demonstrated that the streaks can be reinforced by placing a second array of MVGs downstream of the first one. In this way it is possible to make the control more persistent in the downstream direction. It must be pointed out that the use of MVGs opens also the possibility to set up a control method that acts twofold in the sense that both transition and separation are delayed or even prevented.

JFM classification

Boundary Layers: Boundary layer control Boundary Layers: Boundary layer separation Boundary Layers: Boundary layer stability
Type
Papers
Information
Journal of Fluid Mechanics , Volume 698 , 10 May 2012 , pp. 211 - 234
Copyright
Copyright © Cambridge University Press 2012

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

1. Andersson, P., Berggren, M. & Henningson, D. S. 1999 Optimal disturbances and bypass transition in boundary layers. Phys. Fluids 11, 134–150.CrossRefGoogle Scholar
2. Andersson, P., Brandt, L., Bottaro, A. & Henningson, D. S. 2001 On the breakdown of boundary layers streaks. J. Fluid Mech. 428, 29–60.Google Scholar
3. Asai, M., Minagawa, M. & Nishioka, M. 2002 The instability and breakdown of a near-wall low-speed streak. J. Fluid Mech. 455, 289–314.Google Scholar
4. Bagheri, S. & Hanifi, A. 2007 The stabilizing effect of streaks on TS and oblique waves: a parametric study. Phys. Fluids 19, 078103.CrossRefGoogle Scholar
5. Bakchinov, A. A., Grek, G. R., Klingmann, B. G. B. & Kozlov, V. V. 1995 Transition experiments in a boundary layer with embedded streamwise vortices. Phys. Fluids 7, 820–832.Google Scholar
6. Cossu, C. & Brandt, L. 2002 Stabilization of Tollmien–Schlichting waves by finite amplitude optimal streaks in the Blasius boundary layer. Phys. Fluids 14, L57–L60.Google Scholar
7. Cossu, C. & Brandt, L. 2004 On Tollmien–Schlichting-like waves in streaky boundary layers. Eur. J. Mech. (B/Fluids) 23, 815–833.Google Scholar
8. Elofsson, P. A., Kawakami, M. & Alfredsson, P. H. 1999 Experiments on the stability of streamwise streaks in plane Poiseuille flow. Phys. Fluids 11, 915–930.Google Scholar
9. Fransson, J. H. M. 2010 Turbulent spot evolution in spatially invariant boundary layers. Phys. Rev. E 81, 035301(R).Google Scholar
10. Fransson, J. H. M., Brandt, L., Talamelli, A. & Cossu, C. 2004 Experimental and theoretical investigation of the nonmodal growth of steady streaks in a flat plate boundary layer. Phys. Fluids 16 (10), 3627–3638.CrossRefGoogle Scholar
11. Fransson, J. H. M., Brandt, L., Talamelli, A. & Cossu, C. 2005a Experimental study of the stabilisation of Tollmien–Schlichting waves by finite amplitude streaks. Phys. Fluids 17, 054110.Google Scholar
12. Fransson, J. H. M. & Corbett, P. 2003 Optimal linear growth in the asymptotic suction boundary layer. Eur. J. Mech. (B/Fluids) 22, 259–270.Google Scholar
13. Fransson, J. H. M., Matsubara, M. & Alfredsson, P. H. 2005b Transition induced by free stream turbulence. J. Fluid Mech. 527, 1–25.CrossRefGoogle Scholar
14. Fransson, J. H. M., Talamelli, A., Brandt, L. & Cossu, C. 2006 Delaying transition to turbulence by a passive mechanism. Phys. Rev. Lett. 96, 064501.Google Scholar
15. Holland, M. & Cossu, C. 2009 Adding streamwise streaks in the plane Poiseuille flow. C. R. Méc. 337, 179–183.CrossRefGoogle Scholar
16. Johansson, A. V. & Alfredsson, P. H. 1982 On the structure of turbulent channel flow. J. Fluid Mech. 122, 295–314.Google Scholar
17. Kachanov, Y. S. & Tararykin, O. I. 1987 Experimental investigation of a relaxing boundary layer. Izv. SO Akad. Nauk SSSR, Ser. Tech. Nauk 18, 9–19.Google Scholar
18. Kendall, J. M. 1990 The effect of small-scale roughness on the mean flow profile of a laminar boundary layer. In Instability and Transition (ed. Hussaini, M. Y. & Voigt, R. G. ), pp. 296–302. Springer.Google Scholar
19. Landahl, M. T. 1980 A note on an algebraic instability of inviscid parallel shear flows. J. Fluid Mech. 98, 243–251.Google Scholar
20. Lindgren, B. & Johansson, A. V. 2002 Evaluation of the flow quality in the MTL wind-tunnel. Tech Rep. KTH/MEK/TR-02/13-SE, KTH Mechanics, Stockholm.Google Scholar
21. Lögdberg, O., Fransson, J. H. M. & Alfredsson, P. H. 2009 Streamwise evolution of longitudinal vortices in a turbulent boundary layer. J. Fluid Mech. 623, 27–58.CrossRefGoogle Scholar
22. Matsubara, M., Alfredsson, P. H. & Westin, K. J. A. 1998 Boundary layer transition at high levels of free stream turbulence. ASME Paper 98-GT-248.CrossRefGoogle Scholar
23. Pauley, W. R. & Eaton, J. K. 1988 Experimental study of the development of longitudinal vortex pairs embedded in a turbulent boundary layer. AIAA J. 26, 816–823.CrossRefGoogle Scholar
24. Pearcey, H. H. 1961 Shock-induced separation and its prevention. In Boundary Layer and Flow Control, Its Principle and Applications (ed. Lachmann, G. V. ). Pergamon.Google Scholar
25. Radeztsky, R. H. Jr., Reibert, M. S. & Saric, W. S. 1999 Effect of isolated micron-sized roughness on transition in swept-wing flows. AIAA J. 37 (11).CrossRefGoogle Scholar
26. Saric, W. S., Carrillo, R. B. Jr. & Reibert, M. S. 1998 Leading-edge roughness as a transition control mechanism. AIAA Paper 98-0781.CrossRefGoogle Scholar
27. Saric, W. S. & Reed, H. L. 2002 Supersonic laminar flow control on swept wings using distributed roughness. AIAA Paper 02-0147.Google Scholar
28. Tani, I. & Komoda, H. 1962 Boundary layer transition in the presence of streamwise vortices. J. Aerosp. Sci. 29, 440.Google Scholar
29. Westin, K. J. A., Boiko, A. V., Klingmann, B. G. B., Kozlov, V. V. & Alfredsson, P. H. 1994 Experiments in a boundary layer subject to free stream turbulence. Part I. Boundary layer structure and receptivity. J. Fluid Mech. 281, 193–218.Google Scholar
30. White, E. B. 2002 Transient growth of stationary disturbances in a flat plate boundary layer. Phys. Fluids 14, 4429–4439.Google Scholar
31. White, E. B. & Saric, W. S. 2000 Application of variable leading-edge roughness for transition control on swept wings. AIAA Paper 00-0283.CrossRefGoogle Scholar