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
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.
