Clarification on Drag-Reduction Effect of 3-Dimensional Riblet with Dual-Plane Stereoscopic PIV

2014 Fiscal Year Final Research Report

• Project/Area Number: 24560186
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Fluid engineering
• Research Institution: Tokyo University of Agriculture and Technology
• Principal Investigator: IWAMOTO Kaoru 東京農工大学, 工学(系)研究科(研究院), 准教授 (50408712)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 乱流 / 抵抗低減 / PIV / 数値シミュレーション / リブレット

Outline of Final Research Achievements

The drag-reduction effect of an innovative three-dimensional riblet is evaluated, and world's largest drag-reduction rate of 12% is obtained. Vortical structures in wall turbulence over the riblet surface are investigated by means of a dual-plane stereoscopic particle image velocimetry measurement. It is found that the drag-reduction mechanism is similar to those of two-dimensional riblets. A different point is that the present riblet respectively induces a downward and upward flows in the expanded and contracted regions, which prevent vortices from hitting the bottom wall with wider lateral spacing of the riblet. In consequence, the wetted area of the present riblet is smaller than those of two-dimensional riblets, resulting in the high drag-reduction effect.

Free Research Field

熱流体工学