Active and passive in-plane wall fluctuations in turbulent channel flows

T. I. Jozsa (Corresponding Author), E. Balaras, M. Kashtalyan, A. G. L. Borthwick, I. M. Viola

Research output: Contribution to journalArticle

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Abstract

Compliant walls offer the tantalising possibility of passive flow control. This paper examines the mechanics of compliant surfaces driven by wall shear stresses, with solely in-plane velocity response. We present direct numerical simulations of turbulent channel flows at low (Reτ ≈ 180) and intermediate (Reτ ≈ 1000) Reynolds numbers. Inplane spanwise and streamwise active controls proposed by Choi et al. (1994, Journal of Fluid Mechanics 262: 75-110) are revisited in order to characterise beneficial wall fluctuations. An analytical framework is then used to map the parameter space of the proposed compliant surfaces. The direct numerical simulations show that large-scale passive streamwise wall fluctuations can reduce friction drag by at least 3.7±1%, whereas even small-scale passive spanwise wall motions lead to considerable drag penalty. It is found that a well-designed compliant wall can theoretically exploit the drag reduction mechanism of an active control; this may help advance the development of practical active and passive control strategies for turbulent friction drag reduction.
Original languageEnglish
Pages (from-to)689-720
Number of pages32
JournalJournal of Fluid Mechanics
Volume866
Early online date18 Mar 2019
DOIs
Publication statusPublished - 10 May 2019

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channel flow
Channel flow
Drag reduction
Direct numerical simulation
Drag
active control
friction drag
Friction
drag reduction
Fluid mechanics
direct numerical simulation
Flow control
Shear stress
Mechanics
Reynolds number
fluid mechanics
penalties
shear stress
drag

Keywords

  • turbulent boundary layers
  • flow control
  • drag reduction
  • boundary layer control
  • drag-reduction
  • boundary-layer
  • large-scale
  • deformation
  • hydrodynamic stability
  • direct numerical-simulation
  • skin-friction
  • viscous drag
  • compliant surface
  • opposition control

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Active and passive in-plane wall fluctuations in turbulent channel flows. / Jozsa, T. I. (Corresponding Author); Balaras, E.; Kashtalyan, M.; Borthwick, A. G. L.; Viola, I. M.

In: Journal of Fluid Mechanics, Vol. 866, 10.05.2019, p. 689-720.

Research output: Contribution to journalArticle

Jozsa, T. I. ; Balaras, E. ; Kashtalyan, M. ; Borthwick, A. G. L. ; Viola, I. M. / Active and passive in-plane wall fluctuations in turbulent channel flows. In: Journal of Fluid Mechanics. 2019 ; Vol. 866. pp. 689-720.
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