A study to create a drag reducing wall with a heterogeneous porous structure

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02069
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: Osaka Prefecture University
• Principal Investigator: Suga Kazuhiko 大阪府立大学, 工学(系)研究科(研究院), 教授 (60374089)
• Co-Investigator(Kenkyū-buntansha): 桑田 祐丞 大阪府立大学, 工学(系)研究科(研究院), 准教授 (40772851) ; 金田 昌之 大阪府立大学, 工学(系)研究科(研究院), 准教授 (50346855)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 乱流 / 多孔体 / 流動抵抗 / 計測実験 / 数値解析

Outline of Final Research Achievements

To create a drag reducing wall with a heterogeneous porous structure, we conducted the research by both numerical analysis and experiments. The following findings are obtained.
1) It was confirmed that when the porous interface is partially impermeable, the Kelvin-Helmholtz (KH) waves were damped on such a part, and the flow resistance is reduced by up to 11% from the fully permeable structure.2) We found the existence of a region where the flow resistance does not depend on the surface structure of the porous media. It was confirmed that the reason why the turbulence field is less dependent on this surface structure is due to the development and existence of KH waves whose scale is proportional to the channel height.3) We devised a layered porous structure that can suppress the generation of KH waves, and confirmed its effect in experiments.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

多孔体界面乱流の流動計測実験と，それを補完する多孔体構造を詳細に解像した世界でこれまでに例を見ない複雑界面乱流の直接数値解析を行い，多孔体表面構造の非均質性とケルビン-ヘルムホルツ波の生成に関する力学的解明を進めたことの学術的意義は高いと考えている．同時に乱流流動抵抗を低減できる多孔体構造を考案し，試作して特許出願した．さらなる詳細検証が必要であるが，その有効性を評価確認したことの工学的意義も高いと考えている.