Direct numerical simulation of low Reynolds number flows in an open-channel with sidewalls

Younghoon Joung, Sung Uk Choi

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

A direct numerical simulation of low Reynolds number turbulent flows in an open-channel with sidewalls is presented. Mean flow and turbulence structures are described and compared with both simulated and measured data available from the literature. The simulation results show that secondary flows are generated near the walls and free surface. In particular, at the upper corner of the channel, a small vortex called inner secondary flows is simulated. The results show that the inner secondary flows, counter-rotating to outer secondary flows away from the sidewall, increase the shear velocity near the free surface. The secondary flows observed in turbulent open-channel flows are related to the production of Reynolds shear stress. A quadrant analysis shows that sweeps and ejections are dominant in the regions where secondary flows rush in toward the wall and eject from the wall, respectively. A conditional quadrant analysis also reveals that the production of Reynolds shear stress and the secondary flow patterns are determined by the directional tendency of the dominant coherent structures.

Original languageEnglish
Pages (from-to)854-874
Number of pages21
JournalInternational Journal for Numerical Methods in Fluids
Volume62
Issue number8
DOIs
Publication statusPublished - 2010 Mar 1

Fingerprint

Open Channel
Secondary Flow
Secondary flow
Low Reynolds number
Direct numerical simulation
Reynolds number
Reynolds Stress
Quadrant
Shear Stress
Free Surface
Shear stress
Open Channel Flow
Turbulent Channel Flow
Open channel flow
Coherent Structures
Flow Pattern
Sweep
Direct numerical Simulation
Turbulent Flow
Flow patterns

All Science Journal Classification (ASJC) codes

  • Computational Mechanics
  • Mechanics of Materials
  • Mechanical Engineering
  • Computer Science Applications
  • Applied Mathematics

Cite this

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Direct numerical simulation of low Reynolds number flows in an open-channel with sidewalls. / Joung, Younghoon; Choi, Sung Uk.

In: International Journal for Numerical Methods in Fluids, Vol. 62, No. 8, 01.03.2010, p. 854-874.

Research output: Contribution to journalArticle

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N2 - A direct numerical simulation of low Reynolds number turbulent flows in an open-channel with sidewalls is presented. Mean flow and turbulence structures are described and compared with both simulated and measured data available from the literature. The simulation results show that secondary flows are generated near the walls and free surface. In particular, at the upper corner of the channel, a small vortex called inner secondary flows is simulated. The results show that the inner secondary flows, counter-rotating to outer secondary flows away from the sidewall, increase the shear velocity near the free surface. The secondary flows observed in turbulent open-channel flows are related to the production of Reynolds shear stress. A quadrant analysis shows that sweeps and ejections are dominant in the regions where secondary flows rush in toward the wall and eject from the wall, respectively. A conditional quadrant analysis also reveals that the production of Reynolds shear stress and the secondary flow patterns are determined by the directional tendency of the dominant coherent structures.

AB - A direct numerical simulation of low Reynolds number turbulent flows in an open-channel with sidewalls is presented. Mean flow and turbulence structures are described and compared with both simulated and measured data available from the literature. The simulation results show that secondary flows are generated near the walls and free surface. In particular, at the upper corner of the channel, a small vortex called inner secondary flows is simulated. The results show that the inner secondary flows, counter-rotating to outer secondary flows away from the sidewall, increase the shear velocity near the free surface. The secondary flows observed in turbulent open-channel flows are related to the production of Reynolds shear stress. A quadrant analysis shows that sweeps and ejections are dominant in the regions where secondary flows rush in toward the wall and eject from the wall, respectively. A conditional quadrant analysis also reveals that the production of Reynolds shear stress and the secondary flow patterns are determined by the directional tendency of the dominant coherent structures.

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