PIV experiments in rough-wall, laminar-to-turbulent, oscillatory boundary-layer flows

Anna Mujal-Colilles, Jose M. Mier, Kenneth T. Christensen, Allen Bateman, Marcelo H. Garcia

Research output: Contribution to journalArticle

Abstract

Exploratory measurements of oscillatory boundary layers were conducted over a smooth and two different rough beds spanning the laminar, transitional and turbulent flow regimes using a multi-camera 2D-PIV system in a small oscillatory-flow tunnel (Admiraal et al. in J Hydraul Res 44(4):437-450, 2006). Results show how the phase lag between bed shear stress and free-stream velocity is better defined when the integral of the momentum equation is used to estimate the bed shear stress. Observed differences in bed shear stress and phase lag between bed shear stress and free-stream velocity are highly sensitive to the definition of the bed position (y = b). The underestimation of turbulent stresses close to the wall is found to explain such differences when using the addition of Reynolds and viscous stresses to define both the bed shear stress and the phase lag. Regardless of the flow regime, in all experiments, boundary-layer thickness reached its maximum value at a phase near the flow reversal at the wall. Friction factors in smooth walls are better estimated using a theoretical equation first proposed by Batchelor (An introduction to fluid dynamics. Cambridge University Press, Cambridge, 1967) while the more recent empirical predictor of Pedocchi and Garcia (J Hydraul Res 47(4):438-444, 2009a) was found to be appropriate for estimating friction coefficients in the laminar-to-turbulent transition regime.

Original languageEnglish (US)
Article number1633
JournalExperiments in Fluids
Volume55
Issue number1
DOIs
StatePublished - Jan 1 2014

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boundary layer flow
Boundary layer flow
particle image velocimetry
Shear stress
beds
shear stress
Experiments
time lag
Boundary layers
free flow
Friction
Fluid dynamics
Turbulent flow
boundary layer thickness
friction factor
Momentum
Tunnels
Cameras
fluid dynamics
laminar flow

ASJC Scopus subject areas

  • Computational Mechanics
  • Mechanics of Materials
  • Physics and Astronomy(all)
  • Fluid Flow and Transfer Processes

Cite this

PIV experiments in rough-wall, laminar-to-turbulent, oscillatory boundary-layer flows. / Mujal-Colilles, Anna; Mier, Jose M.; Christensen, Kenneth T.; Bateman, Allen; Garcia, Marcelo H.

In: Experiments in Fluids, Vol. 55, No. 1, 1633, 01.01.2014.

Research output: Contribution to journalArticle

Mujal-Colilles, Anna ; Mier, Jose M. ; Christensen, Kenneth T. ; Bateman, Allen ; Garcia, Marcelo H. / PIV experiments in rough-wall, laminar-to-turbulent, oscillatory boundary-layer flows. In: Experiments in Fluids. 2014 ; Vol. 55, No. 1.
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