The thick, turbulent boundary layer on a cylinder: Mean and fluctuating velocities

Lueptow, Richard M.; Leehey, Patrick; Stellinger, T. S.

doi:10.1063/1.865417

Cited by 53 publications

(66 citation statements)

References 19 publications

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“…6,27 The wall shear stress measured using the Preston tubes varied by less than 2.5% from the mean indicating that the boundary layer was essentially axisymmetric. The streamwise mean velocity profile in the boundary layer measured using a hot wire was slightly fuller than predicted by the cylindrical log law of Lueptow et al, 30 but it was within the expected range of variation. A summary of the experimental and flow conditions are provided in Table I, where U ϱ is the free stream velocity, ␦* and are the displacement and momentum thicknesses for a cylindrical boundary layer, 31 and w is the mean wall shear stress.…”

Section: Methodsmentioning

confidence: 81%

Spanwise structure of wall pressure on a cylinder in axial flow

1999

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The spanwise structure of wall pressure fluctuations was measured in an axisymmetric turbulent boundary layer on a cylinder parallel to the mean flow at a momentum thickness Reynolds number of 2530 and a boundary layer thickness to cylinder radius ratio of 4.81. The measurements were made using miniature hearing aid type condenser microphones with spanwise separations of 0°, 10°, 20°, 30°, 60°, and 90°. An improved wall pressure power spectrum was obtained at low frequencies by utilizing a two-point subtraction method to remove low frequency acoustic background noise of the wind tunnel. The spanwise correlations indicate that the spanwise coherent length of the wall pressure is 30°(78/u or 0.11␦͒. The spanwise coherence is weak and concentrated in a frequency band that is substantially lower than the most energetic frequency band of the wall pressure spectrum. A mode number-frequency decomposition of the wall pressure spectrum indicates that the greatest quantity of energy is in the circumferential modes nearest zero. Modes Ϫ4 to 4 contain most of the wall pressure energy. Conditional sampling by pressure peak and VITA detection schemes ͑where VITA was applied to wall pressure to detect strong pressure gradient events͒ indicate that the spanwise extent of the high pressure peaks and high wall pressure gradients is 60°( 156/u or 0.22␦͒.

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Section: Methodsmentioning

confidence: 81%

Spanwise structure of wall pressure on a cylinder in axial flow

1999

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“…There is also evidence for the loss of the shoulder in the far field characteristic of a planar boundary layer. Experimental results (Lueptow et al 1985) show that as a + decreases, the velocity profile may have a logarithmic region, but the slope will be lower. The numerical solutions for the cases with the larger Reynolds numbers and values of a + (cases 9-14) showed this.…”

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

“…Specifically, values taken from Willmarth et al (1976) and Lueptow et al (1985). Values for the experiments will be given in a mixture of units, matching those used in the source papers.…”

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

“…A substantial body of work comes from Lueptow and his colleagues (Lueptow, Leehey & Stellinger 1985;Lueptow & Haritonidis 1987;Lueptow 1988Lueptow , 1990Lueptow & Jackson 1991;Wietrzak & Lueptow 1994;Snarski & Lueptow 1995;Nepomuceno & Lueptow 1997;Bokde, Lueptow & Abraham 1999). These are experimental studies of flow with a Reynolds number of 3 × 10 3 − 5 × 10 3 with the boundary-layer thickness 5-8 times the cylinder radius.…”

Section: Introductionmentioning

confidence: 99%

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Flow along a long thin cylinder

Tutty

2008

J. Fluid Mech.

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Two different approaches have been used to calculate turbulent flow along a long thin cylinder where the flow is aligned with the cylinder. A boundary-layer code is used to predict the mean flow for very long cylinders (length to radius ratio of up to O(10 6 )), with the effects of the turbulence estimated through a turbulence model. Detailed comparison with experimental results shows that the mean properties of the flow are predicted within experimental accuracy. The boundary-layer model predicts that, sufficiently far downstream, the surface shear stress will be (almost) constant. This is consistent with experimental results from long cylinders in the form of sonar arrays. A periodic Navier-Stokes problem is formulated, and solutions generated for Reynolds number from 300 to 5 × 10 4 . The results are in agreement with those from the boundary-layer model and experiments. Strongly turbulent flow occurs only near the surface of the cylinder, with relatively weak turbulence over most of the boundary layer. For a thick boundary layer with the boundary-layer thickness much larger than the cylinder radius, the mean flow is effectively constant near the surface, in both temporal and spatial frameworks, while the outer flow continues to develop in time or space. Calculations of the circumferentially averaged surface pressure spectrum show that, in physical terms, as the radius of the cylinder decreases, the surface noise from the turbulence increases, with the maximum noise at a Reynolds number of O(10 3 ). An increase in noise with a decrease in radius (Reynolds number) is consistent with experimental results.

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“…Willmarth, Shama and lnglis 3 3 aret Lueptow el al. 10 found that an angle as small as 0.05' between the axis of the cylinder and the flov . Near the wall, the measured velocity was prob3bly in error since the hot-wire averages the velocity over the length of the wire, and the ends of the hot-wire were exposed to higher mean velocities than the center of the wire.…”

Section: Measlirements In Cylindrical Boundary Layersmentioning

confidence: 99%