KSME International Journal

, Volume 15, Issue 12, pp 1784–1793 | Cite as

Flow structure of the wake behind an elliptic cylinder close to a free surface

  • Daichin
  • Sang Joon Lee
Special Issue in Flow Visualization


The flow fields around an elliptic cylinder of axis ratio AR=2 adjacent to a free surface were investigated experimentally using a water channel. The main objective is to understand the effect of the free surface on the flow structure in the near-wake. The flow fields were measured by varying the depth of cylinder submergence, for each experimental condition, 350 velocity fields were measured using a single-frame PIV system and ensemble-averaged to obtain the spatial distribution of turbulent statistics. For small submergence depths a large-scale eddy structure was observed in the near-wake, causing a reverse How near the free surface, downstream of the cylinder. As the depth of cylinder submergence was increased, the flow speed in the gap region between the upper surface of the cylinder and the free surface increased and formed a substantial jet flow. The general flow structure of the elliptic cylinder is similar to previous results for a circular cylinder submerged near to a free surface. However, the width of the wake and the angle of downward deflection of the shear layer developed from the lower surface of the elliptic cylinder are smaller than those for a circular cylinder.

Key Words

Elliptic Cylinder PIV Flow Field Free Surface Near Wake 


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  1. Angrilli, F. and Bergamashi, S., 1982, “Investigation of Wall Induced Modifications to Vortex Shedding from a Circular Cylinder,”Journal of Fluids Engineering. Vol. 104, pp. 518–522.CrossRefGoogle Scholar
  2. Bearman, P. W. and Zdravkovich, M. M. 1978, “Flow Around a Circular Cylinder near a Plane Boundary,”Journal of Fluid Mechanics, Vol. 89, pp. 33–47.CrossRefGoogle Scholar
  3. Choi, J. H. and Lee, S. J. 2000, “Ground Effect of Flow Around an Elliptic Cylinder in a Turbulent Boundary Layer,”Journal of Fluids and Structures, Vol. 14, pp. 697–709.CrossRefGoogle Scholar
  4. Lin, J. C, et al. 1995, “Instantaneous Structure of the Near-Wake of a Circular Cylinder: on the Effect of Reynolds Number,”Journal of Fluids and Structures, Vol. 9, pp. 409–418.CrossRefGoogle Scholar
  5. Lin, J. C, et al. 1996, “Controlled Motion of a Cylinder Through a Free Surface: Effect of Depth of Penetration,”Journal of Fluid and Structures, Vol. 10, pp. 309–317.CrossRefGoogle Scholar
  6. Oshkai, P. and Rockwell, D. 1999, “Free Surface Wave Interaction with a Horizontal Cylinder,”Journal of Fluid and Structures, Vol. 13, pp. 935–954.CrossRefGoogle Scholar
  7. Sheridan, J., et al. 1997, “Flow Past a Cylinder Close to a Free Surface,”Journal of Fluid Mechanics, Vol. 33, pp. 1–30.CrossRefGoogle Scholar
  8. Shin, D. S., et al. 2000, “Velocity Field Measurements of Flow Inside Snout of Continuous Hot-Dip Galvanizing Process Using a Single-Frame PIV Technique,”ISIJ Int., Vol. 40, pp. 484–490.CrossRefGoogle Scholar

Copyright information

© The Korean Society of Mechanical Engineers (KSME) 2001

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringPohang University of Science and Technology (POSTECH)PohangKorea

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