Investigation of twin vortices near the interface in turbulent compound open-channel flows using DNS data

Younghoon Joung, Sung-Uk Choi

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The direct numerical simulation of turbulent flows in a compound open channel is described. Mean flows and turbulence structures are provided, and are compared with numerical and measured data available in the literature. The simulated results show that twin vortices are generated near the interface of the main channel and the floodplain and that their maximum magnitude is about 5% of the bulk streamwise velocity. Near the interface, the simulated wall shear stress reaches a maximum, contrary to experimental data. A quadrant analysis shows that both sweeps and ejections become the main contributor to the production of Reynolds shear stresses near the interface. Through the conditional quadrant analysis, it is demonstrated how the directional tendency of dominant coherent structures determines the production of Reynolds shear stress and the pattern of twin vortices near the interface. In addition, the time-dependent characteristics of three-dimensional vortical structures in a compound open-channel flow were investigated using direct numerical simulation (DNS) data.

Original languageEnglish
Pages (from-to)1744-1756
Number of pages13
JournalJournal of Hydraulic Engineering
Volume134
Issue number12
DOIs
Publication statusPublished - 2008 Nov 26

Fingerprint

Open channel flow
open channel flow
Direct numerical simulation
vortex
Shear stress
Vortex flow
shear stress
simulation
Turbulent flow
Turbulence
turbulent flow
floodplain
turbulence
analysis

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Water Science and Technology
  • Mechanical Engineering

Cite this

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abstract = "The direct numerical simulation of turbulent flows in a compound open channel is described. Mean flows and turbulence structures are provided, and are compared with numerical and measured data available in the literature. The simulated results show that twin vortices are generated near the interface of the main channel and the floodplain and that their maximum magnitude is about 5{\%} of the bulk streamwise velocity. Near the interface, the simulated wall shear stress reaches a maximum, contrary to experimental data. A quadrant analysis shows that both sweeps and ejections become the main contributor to the production of Reynolds shear stresses near the interface. Through the conditional quadrant analysis, it is demonstrated how the directional tendency of dominant coherent structures determines the production of Reynolds shear stress and the pattern of twin vortices near the interface. In addition, the time-dependent characteristics of three-dimensional vortical structures in a compound open-channel flow were investigated using direct numerical simulation (DNS) data.",
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Investigation of twin vortices near the interface in turbulent compound open-channel flows using DNS data. / Joung, Younghoon; Choi, Sung-Uk.

In: Journal of Hydraulic Engineering, Vol. 134, No. 12, 26.11.2008, p. 1744-1756.

Research output: Contribution to journalArticle

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