Measurements in the near-wall region of a boundary layer over a wall with large transverse curvature

Michael H. Krane, L. M. Grega, T. Wei

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Measurements of the near-wall velocity field of the flow over cylinders aligned with a uniform flow are presented. The broader objective of this investigation was to quantify and understand the role of transverse curvature in the limit as cylinder diameter approaches zero. The specific goal was to begin with a turbulent boundary layer over a larger radius cylinder and see what happens as the radius is reduced. Spatially and temporally resolved digital particle image velocimetry (DPIV) measurements were made on three different radius cylinders, 0.14 cm ≤a ≤3.05 cm, extending along the length of a large free-surface water tunnel. Mean and fluctuating profiles are presented at a fixed streamwise location and free-stream speed. For the first time, spatially resolved measurements were made very close to the wall, permitting direct determination of wall shear stress, i.e. u, from near-wall velocity profiles. The measurements revealed a region close to the wall for small radii where the mean streamwise velocity profile is inflectional. This has significant implications on assumptions regarding what happens in the limit of a vanishing cylinder radius.

Original languageEnglish (US)
Pages (from-to)33-50
Number of pages18
JournalJournal of Fluid Mechanics
Volume664
DOIs
StatePublished - Dec 10 2010

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boundary layers
Boundary layers
curvature
radii
velocity distribution
hydraulic test tunnels
uniform flow
Surface waters
Velocity measurement
turbulent boundary layer
free flow
Shear stress
particle image velocimetry
Tunnels
surface water
shear stress
profiles

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

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abstract = "Measurements of the near-wall velocity field of the flow over cylinders aligned with a uniform flow are presented. The broader objective of this investigation was to quantify and understand the role of transverse curvature in the limit as cylinder diameter approaches zero. The specific goal was to begin with a turbulent boundary layer over a larger radius cylinder and see what happens as the radius is reduced. Spatially and temporally resolved digital particle image velocimetry (DPIV) measurements were made on three different radius cylinders, 0.14 cm ≤a ≤3.05 cm, extending along the length of a large free-surface water tunnel. Mean and fluctuating profiles are presented at a fixed streamwise location and free-stream speed. For the first time, spatially resolved measurements were made very close to the wall, permitting direct determination of wall shear stress, i.e. u, from near-wall velocity profiles. The measurements revealed a region close to the wall for small radii where the mean streamwise velocity profile is inflectional. This has significant implications on assumptions regarding what happens in the limit of a vanishing cylinder radius.",
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Measurements in the near-wall region of a boundary layer over a wall with large transverse curvature. / Krane, Michael H.; Grega, L. M.; Wei, T.

In: Journal of Fluid Mechanics, Vol. 664, 10.12.2010, p. 33-50.

Research output: Contribution to journalArticle

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