Phase dependency of near-wall streamwise vortices and associated Reynolds shear stresses close to spanwise oscillating wall

Aiko Yakeno, Yosuke Hasegawa, Nobuhide Kasagi

Research output: Contribution to conferencePaper

Abstract

Direct numerical simulation of fully-developed turbulent channel flow subjected to spanwise harmonic wall oscillation is carried out. The quantitative contributions of quadrant Reynolds shear stresses to the skin friction drag are calculated on the basis of so-called FIK identity [1]. It is found that the Q2 event characterized by upwelling of low-speed fluid away from the wall contributes to the skin friction drag reduction in all oscillation frequencies considered, whereas the Q4 event characterized by downwelling of high speed fluid toward the wall first contributes to drag reduction at small oscillation periods, and then to drag increase significantly with increasing the oscillation period. The conditional averaging technique is applied to near-wall streamwise vortices in order to explain different behavior of Q2 and Q4 with respect to the oscillation period.

Original languageEnglish
Publication statusPublished - 2020 Jan 1
Externally publishedYes
Event14th European Turbulence Conference, ETC 2013 - Lyon, France
Duration: 2013 Sep 12013 Sep 4

Conference

Conference14th European Turbulence Conference, ETC 2013
CountryFrance
CityLyon
Period13/9/113/9/4

ASJC Scopus subject areas

  • Acoustics and Ultrasonics
  • Astronomy and Astrophysics
  • Atmospheric Science
  • Geophysics

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    Yakeno, A., Hasegawa, Y., & Kasagi, N. (2020). Phase dependency of near-wall streamwise vortices and associated Reynolds shear stresses close to spanwise oscillating wall. Paper presented at 14th European Turbulence Conference, ETC 2013, Lyon, France.