Journal of Mechanical Science and Technology

The Korean Society of Mechanical Engineers (대한기계학회)
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Flow Structure of the Wake behind an Elliptic Cylinder Close to a Free Surface

  • Daichin (Department of Mechanical Engineering, Pohang University of Science and Technology) ;
  • Lee, Sang-Joon (Department of Mechanical Engineering, Pohang University of Science and Technology)
  • Published : 2001.12.01
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Abstract

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 statics. For small submergence depths a large-scale eddy structure was observed in the near-wake, causing a reverse flow 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 tan those for a circular cylinder.

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References

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