• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.9
• /
• pp.751-759
• /
• 2015

In this study, we investigate the Characteristics of the flowfields of a circular cylinder having a small triangular prism at the upstream side. We measure the fluid force on the circular cylinder and obtain a visualization of the flow fields using particle image velocimetry (PIV). The experimental parameters employed were the width ratios (H/B = 0.2~0.6) of the triangular prisms to the circular cylinder's diameter, and the gap ratios (G/B = 0~3) between the circular cylinder and the triangular prism. We observed that the drag reduction rate and Strouhal number of the circular cylinder increased and then decreased with G/B in the case of the same H/B. The drag reduction rate increased with H/B in the case of the same G/B. In the case where the circular cylinder had a small triangular prism, the stagnation regions were represented in the upstream and downstream sides of the circular cylinder.