Skip to main content Accessibility help
×
Home

A stereoscopic visual study of coherent structures in turbulent shear flow

  • Ananda K. Praturi (a1) and Robert S. Brodkey (a1)

Abstract

A visual study of a turbulent boundary-layer flow was conducted by photographing the motions of small tracer particles using a stereoscopic medium-speed camera system moving with the flow. In some experiments, dye injection at the leading edge of the flat plate helped to delineate the outer edge of the boundary layer. The technique allowed the three-dimensional aspects of the flow to be studied in some detail, and in particular allowed axial vortex motions in the wall region to be identified.

The flow was found to exhibit three characteristic regions which can be roughly divided into the wall and outer regions of the boundary layer and an irrotational region, unmarked by dye, outside the instantaneous edge of the boundary layer. Briefly, the outer region of the boundary layer was dominated by transverse vortex motions that formed as a result of an interaction between low-speed and high-speed (sweep) fluid elements in that region. The present results clearly show that bulges in the edge of the boundary layer are associated with transverse vortex motions. In addition, the transverse vortex motions appear to induce massive inflows of fluid from the irrotational region deep into the outer region of the boundary layer. The outer edge of the boundary layer thus becomes further contorted, contributing to the intermittency of the region. Furthermore, the outer-region motions give rise to the conditions necessary for the dominant wall-region activity of ejections and axial vortex motions. It is not the energetic wall-region ejections that move to the outer region and give rise to the contorted edge of the boundary layer as has been suggested by others.

The wall-region axial vortex motions were intense and lasted for a time short compared with the lifetime of outer-region transverse vortex motions. The present results strongly suggest that wall-region vortex motions are a result of interaction between the incoming higher-speed fluid from the outer region of the boundary layer and the outflowing low-speed wall-region fluid. This is in direct contrast to all models that suggest that axial vortex pairs in the wall region are the factor that gives rise to the outflow of low-speed fluid trapped between.

Although all the elements necessary to make up a horseshoe vortex structure riding along the wall were present, such a composite was not observed. However, this could be visualized as a possible model to represent the ensemble average of the flow.

Finally, the massive inflows from the irrotational region were observed to precede the appearance of low- and high-speed fluid elements in the boundary layer, thus completing the deterministic cycle of individual coherent events.

Copyright

References

Hide All
Astonia, B. A. 1972 J. Fluid Mech. 56, 1.
Bakewell, H. P. & Lumley, J. L. 1967 Phys. Fluids 10, 1880.
Blackwelder, R. F. & Kaplan, B. E. 1976 J. Fluid Mech. 76, 86.
Blackwelder, R. F. & Kovasznay, L. S. G. 1972 Phys. Fluids 15, 1545.
Brodkey, B. S., Hershey, H. C. & Corino, E. R. 1971 Turbulence Measurements in Liquids (ed. G. K. Patterson & J. L. Zakin), p. 127. Dept. Chemical Engineering Continuing Education Series, University of Missouri-Rolla.
Brodkey, B. S., Wallace, J. M. & Eckelmann, H. 1974 J. Fluid Mech. 63, 209.
Clark, J. A. & Markland, E. 1970 Aero. J. Roy. Aero. Soc. 74, 243.
Clark, J. A. & Markland, E. 1971 J. Hydraul. Div. A.S.C.E. 97, 1653.
Corino, E. R. 1965 Ph.D. thesis, The Ohio State University, Columbus.
Corino, E. R. & Brodkey, R. S. 1969 J. Fluid Mech. 37, 1.
Davies, P. O. A. L. & Yule, A. J. 1975 J. Fluid Mech. 69, 513.
Eckelmann, H. 1974 J. Fluid Mech. 65, 439.
Falco, R. E. 1974 A.I.A.A. 12th Aerospace Sci. Meeting. A.I.A.A. Paper no. 74–99.
Falco, R. E. 1977 Phys. Fluids Suppl. 20, S124.
Fiedler, H. & Head, M. R. 1966 J. Fluid Mech. 25, 719.
Grass, A. J. 1971 J. Fluid Mech. 50, 233.
Gupta, A. K., Laufer, J. & Kaplan, R. E. 1971 J. Fluid Mech. 50, 493.
Hedley, T. B. & Keffer, J. E. 1974 J. Fluid Mech. 64, 645.
Kaplan, B. E. & Laufer, J. 1969 Proc. Int. Cong. Mech. 12, 236.
Kastrinakis, E. G., Wallace, J. M., Willmarth, W. W., Ghorashi, B. & Brodkey, R. S. 1978 Symp. Turbulence, Berlin. Lecture Notes in Physics. Springer.
Kibens, V. & Kovasznay, L. S. G. 1969 U.S. Govt Rep. no. AD688676.
Kim, H. T., Kline, S. J. & Reynolds, W. C. 1971 J. Fluid Mech. 50, 133.
Kline, S. J., Reynolds, W. C., Schraub, R. A. & Runstadler, P. W. 1967 J. Fluid Mech. 30, 741.
Kovasznay, L. S. G., Kibens, V. & Blackwelder, R. F. 1970 J. Fluid Mech. 41, 283.
Laufer, J. 1975 Ann. Rev. Fluid Mech. 7, 307.
Lu, S. S. & Willmarth, W. W. 1973 J. Fluid Mech. 60, 481.
Nychas, S. G. 1972 Ph.D. thesis, The Ohio State University, Columbus.
Nychas, S. G., Hershey, H. C. & Brodkey, R. S. 1973 J. Fluid Mech. 61, 513.
Offen, G. R. & Kline, S. J. 1974 J. Fluid Mech. 62, 223.
Praturi, A. K. 1972 M.S. thesis, The Ohio State University, Columbus.
Praturi, A. K. 1975 Ph.D. thesis, The Ohio State University, Columbus.
Praturi, A. K., Hershey, H. C. & Brodkey, B. S. 1975 In 4th Biennial Symp. Turbulence in Liquids (ed. G. K. Patterson & J. L. Zakin), p. 345. Dept. Chemical Engineering, University of Missouri-Rolla.
Rao, K. N., Karasimha, R. & Badri narayanan, M. A. 1971 J. Fluid Mech. 48, 339.
Sabot, J. & Comte-Bellot, G. 1976 J. Fluid Mech. 74, 767.
Theodorsen, T. 1952 Proc. 2nd Midwestern Conf. Fluid Mech., Ohio State Univ. pp. 118.
Townsend, A. A. 1970 J. Fluid Mech. 41, 13.
Wallace, J. M. & Brodkey, B. S. 1977 Phys. Fluids 20, 351.
Wallace, J. M., Eckelmann, H. & Brodkey, B. S. 1972 J. Fluid Mech. 54, 29.
Willmarth, W. W. 1975 Adv. in Appl. Mech. 15, 159.
Willmarth, W. W. & Lu, S. S. 1972 J. Fluid Mech. 55, 65.
Willmarth, W. W. & Tu, B. J. 1967 Phys. Fluids 10, S134.
MathJax
MathJax is a JavaScript display engine for mathematics. For more information see http://www.mathjax.org.

A stereoscopic visual study of coherent structures in turbulent shear flow

  • Ananda K. Praturi (a1) and Robert S. Brodkey (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed