Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-26T17:41:24.381Z Has data issue: false hasContentIssue false
  • English
  • Français

Boundary layer stabilization using free-stream vortices

Published online by Cambridge University Press:  30 December 2014

L. Siconolfi ,
S. Camarri  and
J. H. M. Fransson
L. Siconolfi
Affiliation:
Dipartimento di Ingegneria Civile ed Industriale, Università di Pisa, I-561 26 Pisa, Italy
S. Camarri
Affiliation:
Dipartimento di Ingegneria Civile ed Industriale, Università di Pisa, I-561 26 Pisa, Italy
J. H. M. Fransson*
Affiliation:
Linné Flow Centre, KTH-Royal Institute of Technology, SE-100 44 Stockholm, Sweden
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

In this numerical investigation we explore the possibility of applying free-stream vortices as a passive flow control method for delaying the transition to turbulence. The work is motivated by previous experimental studies demonstrating that stable streamwise boundary layer (BL) streaks can attenuate both two- and three-dimensional disturbances inside the BL, leading to transition delay, with the implication of reducing skin-friction drag. To date, successful control has been obtained using physical BL modulators mounted on the surface in order to generate stable streaks. However, surface mounted BL modulators are doomed to failure when the BL is subject to free-stream turbulence (FST), since a destructive interaction between the two is inevitable. In order to tackle free-stream disturbances, such as FST, a smooth surface is desired, which has motivated us to seek new methods to induce streamwise streaks inside the BL. A first step, in a systematic order, is taken in the present paper to prove the control idea of generating free-stream vortices for the attenuation of ordinary Tollmien–Schlichting waves inside the BL. In this proof-of-concept study we show that, by applying a spanwise array of counter-rotating free-stream vortices, inducing streamwise BL streaks further downstream, it is possible to alter the BL stability characteristics to such a degree that transition delay may be accomplished. For the demonstration we use direct numerical simulations along with stability analysis.

JFM classification

Boundary Layers: Boundary layer control Flow Control: Drag reduction Instability: Transition to turbulence
Type
Rapids
Information
Journal of Fluid Mechanics , Volume 764 , 10 February 2015 , R2
Check for updates
Copyright
© 2014 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

Andersson, P., Brandt, L., Bottaro, A. & Henningson, D. S. 2001 On the breakdown of boundary layer streaks. J. Fluid Mech. 428, 29–60.Google Scholar
Bagheri, S. & Hanifi, A. 2007 The stabilizing effect of streaks on TS and oblique waves: a parametric study. Phys. Fluids 19, 078103.Google Scholar
Batchelor, G. K. 1964 Axial flow in trailing line vortices. J. Fluid Mech. 20, 645–658.Google Scholar
Camarri, S., Fransson, J. H. M. & Talamelli, A. 2013 Numerical investigation of the Afrodite transition control strategy. In Progress in Turbulence V (ed. Talamelli, A., Oberlack, M. & Peinke, J.), pp. 65–69. Springer.Google Scholar
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
Cossu, C. & Brandt, L. 2004 On Tollmien–Schlichting-like waves in streaky boundary layers. Eur. J. Mech. (B/Fluids) 23, 815–833.Google Scholar
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.Google Scholar
Fransson, J. H. M., Brandt, L., Talamelli, A. & Cossu, C. 2005 Experimental study of the stabilisation of Tollmien–Schlichting waves by finite amplitude streaks. Phys. Fluids 17, 054110.Google Scholar
Fransson, J. H. M. & Talamelli, A. 2012 On the generation of steady streamwise streaks in flat-plate boundary layers. J. Fluid Mech. 698, 211–234.Google Scholar
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
Kachanov, Y. S. & Tararykin, O. I. 1987 Experimental investigation of a relaxing boundary layer. Proc. Siberian Div. USSR Acad. Sci., Ser. Tech. Sci. 18 (5), 9–19 (in Russian).Google Scholar
Landahl, M. T. 1980 A note on an algebraic instability of inviscid parallel shear flows. J. Fluid Mech. 98, 243–251.Google Scholar
Piot, E., Casalis, G. & Rist, U. 2008 Stability of the laminar boundary layer flow encountering a row of roughness elements: biglobal stability approach and DNS. Eur. J. Mech. B 27, 684–706.Google Scholar
Sattarzadeh, S. S., Fransson, J. H. M., Talamelli, A. & Fallenius, B. E. G. 2014 Consecutive turbulence transition delay with reinforced passive control. Phys. Rev. E 89, 061001(R).Google Scholar
Shahinfar, S., Fransson, J. H. M., Sattarzadeh, S. S. & Talamelli, A. 2013 Scaling of streamwise boundary layer streaks and their ability to reduce skin-friction drag. J. Fluid Mech. 733, 1–32.Google Scholar
Shahinfar, S., Sattarzadeh, S. S. & Fransson, J. H. M. 2014 Passive boundary layer control of oblique disturbances by finite-amplitude streaks. J. Fluid Mech. 749, 1–36.Google Scholar
Shahinfar, S., Sattarzadeh, S. S., Fransson, J. H. M. & Talamelli, A. 2012 Revival of classical vortex generators now for transition delay. Phys. Rev. Lett. 109, 074501.Google Scholar
Tani, I. & Komoda, H. 1962 Boundary layer transition in the presence of streamwise vortices. J. Aero. Sci. 29, 440–444.Google Scholar
Velte, C. M., Hansen, M. O. L. & Okulov, V. L. 2008 Helical structure of longitudinal vortices embedded in turbulent wall-bounded flow. J. Fluid Mech. 619, 167–177.Google Scholar