Local isotropy in turbulent boundary layers at high Reynolds number

Saddoughi, Seyed G.; Veeravalli, Srinivas V.

doi:10.1017/s0022112094001370

Cited by 741 publications

(631 citation statements)

References 24 publications

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“…Because the flow in the inertial subrange is locally homogeneous and isotropic, the scalar wavenumber K can be reasonably approximated by its one-dimensional longitudinal cut as earlier noted. A number of studies have also shown that inertial subrange scaling laws are not sensitive to the local isotropy assumption [20]. Stated differently, inertial subrange scaling laws extend over a much broader range of K values within the inertial subrange when compared to the range of K values inferred from locally-isotropic predictions of velocity components' spectral ratios.…”

Section: A Background and Definitionsmentioning

confidence: 99%

Mean scalar concentration profile in a sheared and thermally stratified atmospheric surface layer

Katul

Chameki

et al. 2013

Phys. Rev. E

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Using only dimensional considerations, Monin and Obukhov proposed a 'universal' stability correction function φc(ζ) that accounts for distortions caused by thermal stratification to the mean scalar concentration profile in the atmospheric surface layer when the flow is stationary, planar homogeneous, fully turbulent, and lacking any subsidence. For nearly six decades, their analysis provided the basic framework for almost all operational models and data interpretation in the lower atmosphere. However, the canonical shape of φc(ζ) and the departure from the Reynold's analogy continue to defy theoretical explanation. Here, the basic processes governing the scalar-velocity cospectrum, including buoyancy and the scaling laws describing the velocity and temperature spectra, are considered via a simplified co-spectral budget. The solution to this co-spectral budget is then used to derive φc(ζ), thereby establishing a link between the energetics of turbulent velocity and scalar concentration fluctuations and the bulk flow describing the mean scalar concentration profile. The resulting theory explains all the canonical features of φc(ζ), including the onset of power-laws for various stability regimes and their concomitant exponents, as well as the causes of departure from Reynold's analogy.

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Section: A Background and Definitionsmentioning

confidence: 99%

Mean scalar concentration profile in a sheared and thermally stratified atmospheric surface layer

Katul

Chameki

et al. 2013

Phys. Rev. E

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“…Yet, questions remain and laboratory experiments in a single facility in which the boundary conditions are well controlled are few. Using an inertial-subrange scaling that enables use of a linear ordinate, Saddoughi & Veeravalli (1994) were able to show that the inertial subrange and local isotropy do not necessarily coincide -see also Mestayer (1982). Of the two decades exhibiting a -5/3 slope on log-log axes, only the higher one had a spectral shear correlation coefficient approaching zero.…”

Section: Introductionmentioning

confidence: 99%

“…Dual studies are limited, notable exceptions in shear flows being Saddoughi & Veeravalli (1994); Mydlarski & Warhaft (1996), among others. Many of the ambiguities associated with the definition of the −5/3 inertial subrange law might be clarified by appeal to a unifying physical process.…”

Section: Introductionmentioning

confidence: 99%

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The inertial subrange in turbulent pipe flow: centreline

2016

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The inertial subrange scaling of the axial velocity component is examined for the centre line of turbulent pipe flow for Reynolds numbers in the range 249 Re λ 986. Estimates of the dissipation rate are made by both integration of the one-dimensional dissipation spectrum and the third-order moment of the structure function. In neither case does the non-dimensional dissipation rate asymptote to a constant; rather than decreasing, it increases indefinitely with Reynolds number. Complete similarity of the inertial range spectra is not evident: there is little support for K41, and effects of Reynolds number are not well represented by Kolmogorov's "extended similarity hypothesis", K62. The second-order moment of the structure function does not show a constant value, even when compensated by K62. When corrected for the effects of finite Reynolds number, the third-order moments of the structure function accurately support the " 4 5 ths" law, but they do not show a clear plateau. In common with recent work in grid turbulence, nonequilibrium effects can be represented by an heuristic scaling that includes a global Reynolds number as well as a local one. It is likely that nonequilibrium effects appear to be particular to the nature of the boundary conditions. Here, the principal effects of the boundary conditions appear through finite turbulent transport at the pipe centre line which constitutes a source or a sink at each wavenumber.

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“…The small level of anisotropy in ε u i u j for z/δ > 0.1 can be attributed to the relatively low Reynolds number of the DNS of Spalart (1988). For a rough-wall boundary layer, the experiments of Saddoughi and Veeravalli (1994) and Saddoughi (1997) confirm that at this altitude there is also local isotropy of ε u i u j at high Reynolds numbers. Some studies even conclude that the roughness increases the degree of isotropy closer to the wall and this impact is greater with three-dimensional roughness .…”

Section: U 2 Evolution Equationmentioning

confidence: 76%

Experimental Investigation of Turbulent Momentum Transfer in a Neutral Boundary Layer over a Rough Surface

Tomas

Eiff

Masson

2010

Boundary-Layer Meteorol

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The turbulent characteristics of the neutral boundary layer developing over rough surfaces are not well predicted with operational weather-forecasting models. The problem is attributed to inadequate mixing-length models, to the anisotropy of the flow and to a lack of controlled experimental data against which to validate numerical studies. Therefore, in order to address directly the modelling difficulties for the development of a neutral boundary layer over rough surfaces, and to investigate the turbulent momentum transfer of such a layer, a set of hydraulic flume experiments were carried out. In the experiments, the mean and turbulent quantities were measured by a particle image velocimetry (PIV) technique. The measured velocity variances and fluxes (u i u j ) in longitudinal vertical planes allowed the vertical and longitudinal gradients (∂/∂z and ∂/∂ x) of the mean and turbulent quantities (fluxes, variances and third-order moments) to be evaluated and the terms of the evolution equations for ∂e/∂t, ∂u 2 /∂t, ∂w 2 /∂t and ∂u w /∂t to be quantified, where e is the turbulent kinetic energy. The results show that the pressure-correlation terms allow the turbulent energy to be transferred equitably from u 2 to w 2 . It appears that the repartition between the constitutive terms of the budget of e, u 2 , w 2 and u w is not significantly affected by the development of the rough neutral boundary layer. For the whole evolution, the transfers of energy are governed by the same terms that are also very similar to the smooth-wall case. The PIV measurements also allowed the spatial integral scales to be computed directly and to be compared with the dissipative and mixing length scales, which were also computed from the data.

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Local isotropy in turbulent boundary layers at high Reynolds number

Cited by 741 publications

References 24 publications

Mean scalar concentration profile in a sheared and thermally stratified atmospheric surface layer

Mean scalar concentration profile in a sheared and thermally stratified atmospheric surface layer

The inertial subrange in turbulent pipe flow: centreline

Experimental Investigation of Turbulent Momentum Transfer in a Neutral Boundary Layer over a Rough Surface

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