Experiments in Fluids

, Volume 42, Issue 2, pp 311–320 | Cite as

Spanwise variations in nominally two-dimensional rough-wall boundary layers

  • R. T. Reynolds
  • P. Hayden
  • I. P. Castro
  • A. G. Robins
Research Article

Abstract

Laboratory experiments have been conducted in two separate boundary layer facilities to investigate steady spanwise variations in mean velocity discovered during studies of developing flows over regular arrays of large roughness elements. Regular spanwise variation was found with a steady wavelength, moderated by the growing boundary layer, which was an integer multiple of the repeating unit of roughness. Amplitude variations greater than ±5% in the mean were found over the roughness and greater than ±10% in turbulence quantities. Due to the dominating nature of this phenomena throughout the layer, care should be taken in undertaking local measurements aimed at identifying flow variations caused by roughness heterogeneity.

Notes

Acknowledgments

Partial funding for this work was from the urban meteorology programme under the Universities Weather Research Network (Natural Environment Research Council Grant DST/26/39). RTR is grateful for support from the School of Engineering Sciences. We thank Mr. T. Lawton at the University of Surrey for consultation. The authors declare that these experiments were completed in compliance with the current laws of the United Kingdom.

References

  1. Adrian R, Meinhart C, Tomkins C (2000) Vortex organization in the outer region of the turbulent boundary layer. J Fluid Mech 422:1–54CrossRefMathSciNetMATHGoogle Scholar
  2. Athanassiadou M, Castro I (2001) Neutral flow over a series of rough hills: a laboratory experiment. Bound Lay Met 101:1–30CrossRefGoogle Scholar
  3. Belcher S, Hunt J (1998) Turbulent flow over hills and waves. Annu Rev Fluid Mech 30:507–538CrossRefMathSciNetGoogle Scholar
  4. Blackwelder R, Swearingen J (1988) The role of inflectional velocity profiles in wall bounded flows. Near Wall Turb, Proceedings of Z Zariac Conference, pp 1–21Google Scholar
  5. Bradshaw P (1965) The effect of wind-tunnel screens on nominally two-dimensional boundary layers. J Fluid Mech 22:679–687CrossRefGoogle Scholar
  6. Cheng H, Castro I (2002) Near wall flow over urban-like roughness. Bound Lay Met 104:229–259CrossRefGoogle Scholar
  7. Fasel H (2002) Numerical investigation of the interaction of the Klebanoff-mode with a Tollmien-Schlichting wave. J Fluid Mech 450:1–33MathSciNetCrossRefMATHGoogle Scholar
  8. Gong W, Taylor P, Dörnbrack A (1996) Turbulent boundary-layer flow over fixed aerodynamically rough two-dimensional sinusoidal waves. J Fluid Mech 312:1–37CrossRefGoogle Scholar
  9. Groth J, Johansson A (1988) Turbulence reduction by screens. J Fluid Mech 197:139–155CrossRefGoogle Scholar
  10. Högström U, Bergström H (1996) Organized turbulence structures in the near-neutral atmospheric surface layer. J Atmos Sci 53(17):2452–2464CrossRefGoogle Scholar
  11. Kendall J (1990) Boundary layer receptivity to freestream turbulence. AIAA Paper 90-1504:1–8MathSciNetGoogle Scholar
  12. Klebanoff P, Tidstrom K (1959) Evolution of amplified waves leading to transition in a boundary layer with zero pressure gradient. NASA Tech Note D 195:1–67Google Scholar
  13. Mehta R (1985) Turbulent boundary layer perturbed by a screen. AIAA J 23(9):1335–1342Google Scholar
  14. Phillips W, Wu Z, Lumley J (1996) On the formation of longitudinal vortices in a turbulent boundary layer over wavy terrain. J Fluid Mech 326:321–341CrossRefMATHGoogle Scholar
  15. Raupach M, Thom A, Edwards I (1980) A wind-tunnel study of turbulent flow close to regularly arrayed rough surfaces. Bound Lay Met 18:373–397CrossRefGoogle Scholar
  16. Reynolds R (2006) Measurements of the structure of urban-type boundary layers. Ph.D thesis, The University of Southampton, Southampton, United KingdomGoogle Scholar
  17. Reynolds R, Hayden P, Robins A, Castro I (2004) Spanwise variation in rough-wall boundary layers. Advances in Turb X. Proc 10th Euro Turb Conf 1:239–242Google Scholar
  18. Tan-Atichat J, Nagib H, Loehrke R (1982) Interaction of free-stream turbulence with screens and grids: a balance between turbulence scales. J Fluid Mech 114:501–528CrossRefGoogle Scholar
  19. Tomkins C, Adrian R (2003) Spanwise structure and scale growth in turbulent boundary layers. J Fluid Mech 490:37–74CrossRefMATHGoogle Scholar
  20. Watmuff J (1998) Detrimental effects of almost immeasurably small freestream nonuniformities generated by wind-tunnel screens. AIAA J 36(3):379–386CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • R. T. Reynolds
    • 1
    • 2
  • P. Hayden
    • 3
  • I. P. Castro
    • 1
  • A. G. Robins
    • 3
  1. 1.School of Engineering SciencesUniversity of SouthamptonSouthamptonUK
  2. 2.Advanced Development ProgramsLockheed Martin AeronauticsPalmdaleUSA
  3. 3.Fluids Research CentreUniversity of SurreyGuildfordUK

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