Effect of Groove Shape on Flow Characteristics around a Circular Cylinder with Grooves

  • Authors:

  • Y. Yamagishi;M. Oki

  • Affiliations:

  • Department of Mechanical Engineering, Kanagawa Institute of Technology, 1030 Shimoogino, Atugi-shi, Kanagawa 243-0292, Japan. E-mail: yamagisi@me.kanagawa-it.ac.jp;School of High-Technology for Human Welfare, Tokai University, 317 Nishino, Numazu-shi, Shizuoka 410-0395, Japan

  • Venue:
  • Journal of Visualization
  • Year:
  • 2004

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Abstract

In the flow around a circular cylinder, a sudden decrease in the drag force occurs at a high Reynolds number, but the same phenomenon occurs at a lower Reynolds number in the case where there exist grooves or roughness on the circular cylinder surface. In this paper, in order to make clear the flow characteristics around a circular cylinder in the case of changing the shapes of grooves, the drag coefficient, pressure distribution, velocity distribution and turbulent distribution were measured. Moreover the flow around the cylinder was analyzed by applying the RNG k −ε turbulent model, and the surface flow pattern was investigated using the oil-film technique. From these results, it is clear that the drag coefficient of a circular cylinder with triangular grooves decreases by about 15% compared with that of a circular cylinder with arc grooves.