• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to project page

1995 Fiscal Year Final Research Report Summary

Clarification of Drag-Reduction-Mechanism over a Riblet surface and Exploration of Geometry of Riblet

Research Project

Project/Area Number 06650200
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Fluid engineering
Research InstitutionGIFU UNIVERSITY

Principal Investigator

YAMASHITA Shintaro  Gifu University Faculty of Engineering, Mechanical engineering, Professor, 工学部, 教授 (20023236)

Co-Investigator(Kenkyū-buntansha) INOUE Yoshihiro  Suzuka College of Technology, Mechanical Engineering, Assistant Professor, 機械工学科, 講師 (00176455)
Project Period (FY) 1994 – 1995
KeywordsRiblet / Skin-Friction / Drag Reduction / Wall Jet / Turbulence
Research Abstract

This research is intended to investigate the effect that riblets reduce skin-friction in a wall jet and to make it clear that this is due to modify the turbulent structure in the near wall jet. So far, it is cleared that the local skin-friction estimated from the mean velocity profiles indicates the reduction rate of the drag.
The principal results got for the term of project concerned are as follows.
1.The larger size riblet surface was made and it was recognized that the local skin-friction estimated from the mean velocity profiles indicates larger reduction ratio at the larger position than the former non-dimensional riblet width.
2.In the region where the drug reduction due to the riblets yields.the probability density functions for fluctuating velocity near the wall show approximately Gaussian distribution.
3.From the analysis of the VITA technique, the bursting wave is observed even in the wall jet, however the time scale is ten times as long as that in turbulent boundary layr.
The results of the four-quadrant method exhibit that the mechanism of generating to the Reynolds stress is become weak due to the riblets.
4.The correlation length of the fluctuating velocity increase in the x-direction and z-direction due to the riblets. The integral scales near the wall in spanwise direction above the riblet surface are larger in comparison with the flat surface and the spanwise scales of large eddy are large.
5.The spanwise spectrum in the wall jets increase as the wave length increasing within the inner layr. This shows the difference from the turbulent structure in the boundary layr and a discrepancy of the riblet scale that the maximum reduction ratio occurred is attributed to the difference in the turbulent structure like this.
6.The results in the direct method in a wall jet on the flat surface belong to the range of the scatter the indirect meathod by the other research worker and these data are reliable.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] 山下新太郎: "リブレット面に沿う壁面噴流に関する実験的研究(平均・変動速度場と抵抗減少の評価)" 日本機械学会論文集B編. 60. 1145-1151 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 山下新太郎: "リブレット面上の壁面噴流の構造" 第26回乱流シンポジウム-ながれ別冊. 13. 326-329 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Shintaro YAMASHITA: "Structure of a Wall Jet over a Riblet Surface" 10th Symposium on Turbulent Shear Flows. 2. 14-1-14-6 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 山下新太郎: "リブレットに沿う壁面噴流に関する実験的研究(壁面近傍の乱流構造の変化)" 日本機械学会論文集B編. 61. 2849-1855 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 井上吉弘: "リブレット面上の壁面噴流の抵抗減少" 流体熱工学研究. (掲載予定).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Shintaro YAMASHITA: "An Exprerimental Study on the Wall Jet over a Riblet Surface (Measurement of Mean and Fluctuating Velocities and Estimation of Drag Reduction)" JSME International Journal,Ser.II. (掲載予定).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Shintaro YAMASHITA: "An Experimental Study on the Wall Jet over a Riblet Surface (Measurement of Mean and Fluctuating Velocities and Estimation of Drag Reduction)" Trans.JSME Scr.B (in Japanese). 60-572. 1145-1151 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Shintaro YAMASHITA: "Structure of Wall Jet over a Riblet Surface" 26th Symposium on Turbulent Flows-Nagare Suppl. (in Japanese). 13. 326-329 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Shintaro YAMASHITA: "Structure of a Wall Jet over a Riblet Surface" 10th Symposium on Turbulent Shear Flows. 2. 14.1-14.6 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Shintaro YAMASHITA: "An Experimental Study on the Wall Jet over a Riblet Surface (Modification of Turbulent Structure near the Wall)" Trans.JSME Scr.B (in Japanese). 61-588. 2849-2855 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yoshihiro INOUE: "Drag Reduction of the Wall Jet over a Riblet Surface" Fluid & Heat Engineering Research (in Japanese). (to appear).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Shintaro YAMASHITA: "An Experimental Study on the Wall Jet over a Riblet Surface (Measurement of Mean and Fluctuating Velocities and Estimation of Drag Reduction)" JSME Internatina Journal Ser.II. (to appear).

    • Description
      「研究成果報告書概要(欧文)」より

URL: 

Published: 1997-03-04  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi