Reynolds number and roughness effects on turbulent stresses in sandpaper roughness boundary layers

Morrill-Winter, Caleb; Squire, Dougal T.; Klewicki, Joseph; Hutchins, Nicholas; Schultz, Michael P.; Marušić, Ivan

doi:10.1103/physrevfluids.2.054608

Cited by 12 publications

(42 citation statements)

References 47 publications

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“…As was previously observed by Morrill-Winter et al [64] and Morrill-Winter et al [59] in smoothand rough-wall flows, respectively, the location and magnitude of the peak in w 2 + appears to increase with increasing friction Reynolds number. Particularly for the smooth-wall profiles in Fig.…”

Section: Tower Piv Statisticssupporting

confidence: 81%

“…The latter attempts to isolate from the comparisons inherent trends in the rough-and smooth-wall data with δ + . Similar matched δ + comparisons were made by Squire et al [19] and Morrill-Winter et al [59] using HWA data, with more in-depth discussions and demonstrations of the rationale provided therein.…”

Section: Piv Noisesupporting

confidence: 62%

“…This is contrary to the classically assumed k or δ scaling. Squire et al [19] and Morrill-Winter et al [59] adopt the Mehdi et al [42] scaling, using the empirical formulation for z m provided therein, and show that for the present rough surface an inertial subdomain spanning 2.5×z m < z < 0.19δ 99 is consistent with the classical features of the logarithmic region. Hence, these same bounds are employed in the present study, where, from Mehdi et al [42], for the present roughness regime [z m /k s > O(1)]:…”

Section: Boundary Layer Parametersmentioning

confidence: 63%

“…The "Type" indicates which velocity components are resolved by the hot-wire measurement: "−" means that only u fluctuations are measured, and "×" means that both u and w fluctuations are measured simultaneously. The wire length in each HWA measurement is denoted using l. H09, T14, S16, and M16 refer to Hutchins et al [61], Talluru et al [71], Squire et al [19], and Morrill-Winter et al [59] matched k + s . In Fig.…”

Section: Piv Noisementioning

confidence: 99%

“…It is worth noting here that Townsend's wall-similarity hypothesis is posed external to "the flow patterns set up by individual roughness elements" and only over a region that is "fully turbulent and independent of the magnitude of the fluid viscosity." With the classical supposition that the roughness height is the smallest relevant scale in rough-wall flows, it is logical to conclude that the roughness layer should scale on k. However, Mehdi et al [42], and subsequently Squire et al [19] and Morrill-Winter et al [59], provide evidence that ν/U τ is an important parameter in rough-wall flows. If this is the case, then in certain flows Townsend's criteria for wall similarity may only be satisfied in the region where viscosity is negligible; i.e., in the inertial region of the flow.…”

Section: B Smooth-and Rough-wall Comparisonsmentioning

confidence: 99%

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Smooth- and rough-wall boundary layer structure from high spatial range particle image velocimetry

et al. 2016

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Two particle image velocimetry arrangements are used to make true spatial comparisons between smooth-and rough-wall boundary layers at high Reynolds numbers across a very wide range of streamwise scales. Together, the arrangements resolve scales ranging from motions on the order of the Kolmogorov microscale to those longer than twice the boundary layer thickness. The rough-wall experiments were obtained above a continuous sandpaper sheet, identical to that used by Squire et al. [J. Fluid Mech. 795, 210 (2016)], and cover a range of friction and equivalent sand-grain roughness Reynolds numbers (12 000 δ + 18000, 62 k + s 104). The smooth-wall experiments comprise new and previously published data spanning 6500 δ + 17 000. Flow statistics from all experiments show similar Reynolds number trends and behaviors to recent, well-resolved hot-wire anemometry measurements above the same rough surface. Comparisons, at matched δ + , between smooth-and rough-wall two-point correlation maps and two-point magnitude-squared coherence maps demonstrate that spatially the outer region of the boundary layer is the same between the two flows. This is apparently true even at wall-normal locations where the total (inner-normalized) energy differs between the smooth and rough wall. Generally, the present results provide strong support for Townsend's [The Structure of Turbulent Shear Flow (Cambridge University Press, Cambridge, 1956), Vol. 1] wall-similarity hypothesis in high Reynolds number fully rough boundary layer flows.

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Section: Tower Piv Statisticssupporting

confidence: 81%

Section: Piv Noisesupporting

confidence: 62%

Section: Boundary Layer Parametersmentioning

confidence: 63%

Section: Piv Noisementioning

confidence: 99%

Section: B Smooth-and Rough-wall Comparisonsmentioning

confidence: 99%

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Smooth- and rough-wall boundary layer structure from high spatial range particle image velocimetry

et al. 2016

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Reynolds number dependence of Reynolds and dispersive stresses in turbulent channel flow past irregular near-Gaussian roughness

Jelly

Busse

2019

International Journal of Heat and Fluid Flow

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The spatial structure of the logarithmic region in very-high-Reynolds-number rough wall turbulent boundary layers

et al. 2018

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Using super-large-scale particle image velocimetry (SLPIV), we investigate the spatial structure of the near-wall region in the fully rough atmospheric surface layer with Reynolds number$Re_{\unicode[STIX]{x1D70F}}\sim O(10^{6})$. The field site consists of relatively flat, snow-covered farmland, allowing for the development of a fully rough turbulent boundary layer under near-neutral thermal stability conditions. The imaging field of view extends from 3 m to 19 m above the ground and captures the top of the roughness sublayer and the bottom of an extensive logarithmic region. The SLPIV technique uses natural snowfall as seeding particles for the flow imaging. We demonstrate that SLPIV provides reliable measurements of first- and second-order velocity statistics in the streamwise and wall-normal directions. Our results in the logarithmic region show that the structural features identified in laboratory studies are similarly present in the atmosphere. Using instantaneous vector fields and two-point correlation analysis, we identify vortex structures sharing the signature of hairpin vortex packets. We also evaluate the zonal structure of the boundary layer by tracking uniform momentum zones (UMZs) and the shear interfaces between UMZs in space and time. Statistics of the UMZs and shear interfaces reveal the role of the zonal structure in determining the mean and variance profiles. The velocity difference across the shear interfaces scales with the friction velocity, in agreement with previous studies, and the size of the UMZs scales with wall-normal distance, in agreement with the attached eddy framework.

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Reynolds number and roughness effects on turbulent stresses in sandpaper roughness boundary layers

Cited by 12 publications

References 47 publications

Smooth- and rough-wall boundary layer structure from high spatial range particle image velocimetry

Smooth- and rough-wall boundary layer structure from high spatial range particle image velocimetry

Reynolds number dependence of Reynolds and dispersive stresses in turbulent channel flow past irregular near-Gaussian roughness

The spatial structure of the logarithmic region in very-high-Reynolds-number rough wall turbulent boundary layers

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