THERMAL SCIENCE

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Ali Kahraman

,

Muammer Özgören

,

Beşir Şahin

FLOW STRUCTURE FROM A HORIZONTAL CYLINDER COINCIDENT WITH A FREE SURFACE IN SHALLOW WATER FLOW

ABSTRACT
Vortex formation from a horizontal cylinder coincident with a free surface of a shallow water flow having a depth of 25.4 [mm] was experimentally investigated using the PIV technique. Instantaneous and time-averaged flow patterns in the wake region of the cylinder were examined for three different cylinder diameter values under the fully developed turbulent boundary layer condition. Reynolds numbers were in the range of 1124£ Re£ 3374 and Froude numbers were in the range of 0.41 £ Fr £ 0.71 based on the cylinder diameter. It was found that a jet-like flow giving rise to increasing the flow entrainment between the core and wake regions depending on the cylinder diameter was formed between the lower surface of the cylinder and bottom surface of the channel. Vorticity intensity, Reynolds stress correlations and the primary recirculating bubble lengths were grown to higher values with increasing the cylinder diameter. On the other hand, in the case of the lowest level of the jet-like flow emanating from the beneath of the smallest cylinder, the variation of flow characteristics were attenuated significantly in a shorter distance. The variation of the reattachment location of the separated flow to the free-surface is a strong function of the cylinder diameter and the Froude number.
KEYWORDS
horizontal cylinder, PIV, reattachment, shallow water flow, vorticity, wake region
PAPER SUBMITTED: 2011-07-19
PAPER REVISED: 2011-07-20
PAPER ACCEPTED: 2011-07-20
DOI REFERENCE: https://doi.org/10.2298/TSCI110719087K
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2012, VOLUME 16, ISSUE Issue 1, PAGES [93 - 107]
REFERENCES
  1. Kahraman, A., Sahin, B. and Rockwell, D., Control of vortex formation from a vertical cylinder in shallow water: Effect of localized roughness elements, Experiments in Fluids, 33 (2002), pp. 54-65
  2. Akilli, H. and Rockwell, D., Vortex formation from a cylinder in shallow water, Physics of Fluids 14 (2002), 9, pp. 2957-2967
  3. Lin, J. C., Ozgoren, M. and Rockwell, D., Space-time development of the onset of a shallow-water vortex. Journal Fluid Mechanics, 485 (2003), pp. 33-66
  4. Ingram, R. G. and Chu, V. H., Flow around island in Rupert Bay: an investigation of the bottom friction effect, Journal of Geophysical Research, 92 (1987), pp. 14521-14533
  5. Chen, D. and Jirka, H., Experimental study of plane turbulent wakes in a shallow water layer, Fluid Dynamics Research, 16 (1995), pp. 11-41
  6. Akilli, H., Akar, A. and Karakus, C., Flow characteristics of circular cylinders arranged side-by-side in shallow water, Flow Measurement Instrumentation, 15 (2004), pp. 87-197
  7. Triantafyllou, G. S. and Dimas A. A., The low Froude number wake of floating bluff objects, Internal Report MITSG89-5, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA, 1989a
  8. Triantafyllou G. S. and Dimas A. A. Interaction of two-dimensional separated flows with a free surface at low Froude numbers. Physics of Fluids A 1 (1989b), pp. 1813-1821
  9. Yu, D. and Tryggvason, G., The free surface signature of unsteady two dimensional vortex flows. Journal of Fluid Mechanics, 218 (1990), pp. 547-572
  10. Tryggvason, G., Unverdi, S. O., Song M. and Abdolahi-Alibeik J., Interaction of vortices with a free surface and density interfaces, in: Vortex Dynamics and Vortex Methods, In Lectures in Applied Mathematics (Ed. C. R. Anderson and C. Greengard), American Mathematical Society, 28, 1991, pp. 679-699
  11. Rood, E. P., Vorticity interactions with a free surface, in: Fluid Vortices, (Ed. S. I. Green), Kluwer Inc., 1995, pp. 687-730
  12. Sheridan, J., Lin, J. C. and Rockwell, D., Metastable states of a cylinder wake adjacent to a free surface, Physics of Fluids, 7 (1995), pp. 2099-2101
  13. Sheridan, J., Lin, J. C. and Rockwell, D., Flow past a cylinder close to a free surface. Journal of Fluid Mechanics, 330 (1997), pp. 1-30
  14. Hoyt, J. W. and Sellin, R. H. J., A comparison of the tracer and PIV results in visualizing water flow around a cylinder close to the free surface, Experiments in Fluids, 28 (2000), pp. 261-265
  15. Bearman, P. W. and Zdravkovich, M. M., Flow around a circular cylinder near a plane boundary. Journal of Fluid Mechanics, 89 (1978), pp. 33-47.
  16. Reichl, P. J., Hourigan, K. and Thompson, M. C., The unsteady wake of a circular cylinder near a free surface, Flow, Turbulence and Combustion, 71 (2003), pp. 347-359.
  17. Reichl, P. J., Hourigan, K. and Thompson, M. C., Flow past a cylinder close to a free surface, Journal of Fluid Mechanics, 533 (2005), pp. 269-296.
  18. Ozturk, N. A., Akkoca, A. and Sahin, B., Flow details of a circular cylinder mounted on a flat plate, Journal of Hydraulic Research, 46 (2008), 3, pp. 334-355.
  19. Sahin, B. and Ozturk, N. A., Behaviour of flow at the junction of cylinder and base plate in deep water, Measurement, 42 (2009), pp. 225-240.
  20. Kirkgöz, M. S. and Ardiçlioğlu, M. Velocity profiles of developing and developed open channel flow, Journal of Hydraulic Engineering, 123 (1997), pp. 1099-1105.
  21. Klenanoff, P. S., Characteristics of turbulence in a boundary layer with zero pressure gradient, NACA Technical Notes, No. 1347, Washington, D. C, USA, 1955
  22. Purtell, L. P., Klebanoff, P. S. and Buckley, F. T., Turbulent boundary layer at low Reynolds numbers, Physics of Fluid, 24 (1981), pp. 802-811.
  23. Johansen, J. B. and Smith, C. R., The effects of cylindrical surface modification on turbulent boundary layers, Report FM-3, Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA, USA, 1983.
  24. Adrian, R. J., Particle-imaging techniques for experimental fluid mechanics, Annual Review of Fluid Mechanics, 23 (1991), pp. 261-304.
  25. Westerweel, J., Digital particle image velocimetry, theory and application, Delft University Press, Netherlands, 1993.
  26. Keane, R. D. and Adrian, R. J., Optimization of particle image velocimeters, Optical Methods in Flow and Particle Diagnostics, 68 (1989), pp. 139-59.
  27. Fouras, A. and Soria, J., Accuracy of out-of-plane vorticity measurements derived from in-plane velocity field data, Experiments in Fluids, 25 (1998), pp. 409-430.
  28. Ozgoren, M., Flow structure in the downstream of square and circular cylinders, Flow Measurement Instrumentation, 17 (2006), pp. 225-235.
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Flow structure from a horizontal cylinder coincident with a free surface in shallow water flow

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