Full Content is available to subscribers

Subscribe/Learn More  >

Near-Wall Turbulence of Drag Reduction and Promotion in Unsteady Turbulent Pipe Flows

[+] Author Affiliations
Toshihiro Takami, Yoshinori Kita

Okayama University of Science, Okayama, Japan

Paper No. FEDSM2003-45222, pp. 2617-2622; 6 pages
  • ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference
  • Volume 1: Fora, Parts A, B, C, and D
  • Honolulu, Hawaii, USA, July 6–10, 2003
  • Conference Sponsors: Fluids Engineering Division
  • ISBN: 0-7918-3696-7 | eISBN: 0-7918-3673-8
  • Copyright © 2003 by ASME


An unsteady behavior of the wall-drag, the velocity and the turbulence is experimentally investigated in the unsteady turbulent pipe flow, under several flow conditions with a rapid to slow time-variation and a large distortion of the flow-rate imposed stepwise. The instantaneous wall-shear stress and three-components of instantaneous velocities are simultaneously measured using the HWA technique of a surface hot-wire and a non-orthogonal triple-sensors probe. In the present study, to understand the unsteady behavior of the relation between the wall-drag and the velocity distribution, the unsteady response of the turbulence to the imposed unsteady flow is investigated by analyzing the relation between the unsteady Reynolds stress and the instantaneous velocity fluctuation during the accelerating and decelerating phase. It is found that, near the pipe-wall, the statistical parameter of the phase-average turbulence structure and the phase-average quadrant contribution rate of instantaneous velocity fluctuations to the Reynolds stress are almost similar to those in the steady turbulent flow, although the drag-reduction and the drag-promotion occurs during the accelerating and decelerating phase respectively.

Copyright © 2003 by ASME



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In