Experiments in Fluids

, Volume 50, Issue 1, pp 13–21 | Cite as

Particle image velocimetry of a low-Reynolds-number separation bubble

Research Article


Boundary-layer separation at a backward-facing step of a flat plate has been investigated in a low-turbulence wind tunnel with high-speed Particle Image Velocimetry (PIV). The experiments focused on the flow pattern behind the step at the Reynolds number based on its height of about 1,000. Under quiet environmental and low-Re-number conditions, laminar-flow separation was observed behind the step subjected to a small amount of the shear-layer instability. Examination of natural and controlled velocity perturbations in the separation region indicated that the version of PIV used in the present study is an appropriate tool to deal with linear instability details that is normally done through hot-wire measurements.

List of symbols


Oscillation frequency


Step height


Shape factor


Reynolds number


Streamwise component of the mean-flow velocity


External-flow velocity at the step position


Amplitude of the streamwise velocity perturbations


Normal component of the mean-flow velocity


Amplitude of the normal velocity perturbations


Streamwise coordinate


Normal-to-wall coordinate


Transverse coordinate

Greek symbols


Spatial growth rate of velocity disturbances


Hartree parameter


Displacement thickness


Momentum thickness


Kinematic viscosity







Root-mean-square (rms)


  1. Boiko AV (2002) Receptivity of a flat plate boundary layer to a free stream axial vortex. Eur J Mech B/Fluids 21:325–340MATHCrossRefGoogle Scholar
  2. Boiko AV, Dovgal AV, Grek GR, Kozlov VV (2002) Origin of turbulence in near-wall flows. Springer, BerlinMATHGoogle Scholar
  3. Boiko AV, Dovgal AV, Hein S (2005) Experiments on stream-wise streaky structures in a laminar separation bubble. DLR-IB 224-2005 A18Google Scholar
  4. Bradbury LJS, Castro IP (1971) A pulsed-wire technique for velocity measurements in highly turbulent flows. J Fluid Mech 49:657–691CrossRefGoogle Scholar
  5. Canuto C, Hussaini MY, Quarteroni A, Zang TA (2007) Spectral methods: evolution to complex geometries and applications to fluid dynamics. Springer, BerlinMATHGoogle Scholar
  6. Dovgal AV, Kozlov VV, Michalke A (1995) Contribution to the instability of laminar separating flows along axisymmetric bodies. Part 2: experiment and comparison with theory. Eur J Mech B/Fluids 14:351–365Google Scholar
  7. Durbin PA, McKinzie DJ, Durbin EJ (1987) An anemometer for highly turbulent or recirculating flows. Exp Fluids 5:184–188CrossRefGoogle Scholar
  8. Eaton JK, Johnston JP (1981) A review of research on subsonic turbulent flow reattachment. AIAA J 19:1093–1100CrossRefGoogle Scholar
  9. Eaton JK, Jeans AH, Ashjaee J, Johnston JP (1979) A wall-flow-direction probe for use in separating and reattaching flows. J Fluids Eng 101:364–366CrossRefGoogle Scholar
  10. Goldstein RJ, Eriksen VL, Olson RM, Eckert ERG (1970) Laminar separation, reattachment and transition of the flow over a downstream-facing step. J Basic Eng, Trans ASME D 92:732–739Google Scholar
  11. Grant I, Owens EH (1990) Confidence interval estimates in PIV measurements of turbulent flows. Appl Opt 29:1400–1402CrossRefGoogle Scholar
  12. Hudy LM, Naguib A, Humphreys WM (2007) Stochastic estimation of a separated-flow field using wall-pressure-array measurements. Phys Fluids 19:024103–024118CrossRefGoogle Scholar
  13. Kostas J, Soria J, Chong MS (2002) Particle image velocimetry measurements of a backward-facing step. Exp Fluids 33:838–853Google Scholar
  14. Lang M, Rist U, Wagner S (2004) Investigations on controlled transition development in a laminar separation bubble by means of LDA and PIV. Exp Fluids 36:43–52CrossRefGoogle Scholar
  15. Raffel M, Willert CE, Wereley ST, Kompenhans J (2007) Particle image velocimetry—a practical guide. Springer, BerlinGoogle Scholar
  16. Scarano F (2002) Iterative image deformation methods in PIV. Meas Sci Technol 13:R1–R19CrossRefGoogle Scholar
  17. Scarano F, Riethmuller ML (1999) Iterative multigrid approach in PIV image processing with discrete window offset. Exp Fluids 26:513–523CrossRefGoogle Scholar
  18. Shivaprasad BG, Simpson RL (1982) Evaluation of a wall-flow direction probe for measurements in separated flows. J Fluids Eng 104:162–166CrossRefGoogle Scholar
  19. Sinha SN, Gupta AK, Oberai MM (1981) Laminar separating flow over backsteps and cavities, Pt. I: backsteps. AIAA J 19:1527–1530CrossRefGoogle Scholar
  20. Stanislas M, Okamoto K, Kähler CJ, Westerweel J (2005) Main results of the second international PIV challenge. Exp Fluids 39:170–191CrossRefGoogle Scholar
  21. Thompson BE, Whitelaw JH (1984) Flying hot-wire anemometry. Exp Fluids 2:47–55CrossRefGoogle Scholar
  22. Trefethen LN (2000) Spectral methods in Matlab. SIAM, PhiladelphiaMATHGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Khristianovich Institute of Theoretical and Applied MechanicsNovosibirskRussia
  2. 2.Institute of Aerodynamics and Flow TechnologyGerman Aerospace Center (DLR)GöttingenGermany
  3. 3.Institute for Aeronautics and Astronautics (ILR)Technical University of BerlinBerlinGermany

Personalised recommendations