Experimental study on the role of spanwise vorticity and vortex filaments in the outer region of open-channel flow

Qigang Chen, Ronald Adrian, Qiang Zhong, Danxun Li, Xingkui Wang

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

The dynamic importance of spanwise vorticity and vortex filaments has been assessed in steady, uniform open-channel flows by means of particle image velocimetry. By expressing the net force due to Reynoldsf turbulent shear stress, ∂(-uv)/∂y, in terms of two velocity.vorticity correlations, vωz and wωy, the results show that both spanwise vorticity ωz and the portion of it that is due to spanwise filaments make important contributions to the net force and hence the shape of the mean flow profile. Using the swirling strength to identify spanwise vortex filaments, it is found that they account for about 45% of vωz , the remainder coming from non-filamentary spanwise vorticity, i.e. shear. The mechanism underlying this contribution is the movement of vortex filaments away from the wall. The contribution of spanwise vortex filaments to the Reynolds stress is small because they occupy a small fraction of the flow. The contribution of the induced motion of the spanwise vortex filaments is significant.

Original languageEnglish (US)
Pages (from-to)476-489
Number of pages14
JournalJournal of Hydraulic Research
Volume52
Issue number4
DOIs
StatePublished - Jan 1 2014

Keywords

  • Hairpin vortex
  • Net force
  • Open-channel flow
  • Reynolds shear stress
  • Spanwise vortex filament
  • Turbulence

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Water Science and Technology

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