Properties of the streamwise velocity fluctuations in the inertial layer of turbulent boundary layers and their connection to self-similar mean dynamics

Zhou, Ang; Klewicki, Joseph

doi:10.1016/j.ijheatfluidflow.2014.09.009

Cited by 14 publications

(8 citation statements)

References 39 publications

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“…Referencing the Newtonian fluid flow cases (δ + ≅ 1800 experiment, δ + = 2004 DNS), it is apparent that these profiles complete their distinct change in slope near U/U cl = 0.68 at the present δ + . As observed by Zhou & Klewicki (2015) in boundary layers over 1450 δ + 19600 this knee in the curve slowly moves to lower U/U cl with increasing δ + , and the onset of the Reynolds number invariant (approximately linear) region closely corresponds to the start of the inertial domain found from consideration of the MMB. For the DNS, this position is denoted by the solid vertical line in figure 27(a), and by the black diamond symbol for the δ + ≃ 1800 experiment.…”

Section: Diagnostic Plotsupporting

confidence: 67%

“…A logarithmic mean velocity profile stems from this self-similar structure. Zhou & Klewicki (2015) investigated the correspondences between the self-similar inertial domain just described, and that found for other measures of self-similar structure in the canonical boundary layer. Notably, to within the uncertainty of their data they found an exact correspondence between 2.6 √ δ + y + δ + /2 and the domain over which the so-called diagnostic plot of Alfredsson et al (2012) exhibits its (approximately) linear decrease.…”

Section: Diagnostic Plotmentioning

confidence: 91%

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Turbulence Production in the Low Polymer Drag Reduction Regime

Elsnab

White

Klewicki

2019

Springer Proceedings in Physics

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Streamwise velocity profiles and their wall-normal derivatives were used to investigate the properties of turbulent channel flow in the low polymer drag reduction (DR) regime (DR = 6.5% to 26%), as realized via polymer injection at the channel surface. Streamwise velocity data were obtained over a friction Reynolds number ranging from 650 to 1800 using the single velocity component version of molecular tagging velocimetry (1c-MTV). This adaptation of the MTV technique has the ability to accurately capture instantaneous profiles at very high spatial resolution (850 data points per wall-normal profile), and thus generate well-resolved derivative information as well. Owing to this ability, the present study is able to build upon and extend the recent numerical simulation analysis of White et al. (J. Fluid Mech. vol. 834, 2018) that examined the mean dynamical structure of polymer drag reduced channel flow at friction Reynolds numbers up to 1000. Consistently, the present mean velocity profiles indicate that the extent of the logarithmic region diminishes with increasing polymer concentration, while statistically significant increases in the logarithmic profile slope begin to occur for drag reductions less than 15%. Profiles of the streamwise velocity rms indicate that the maximum moves farther from the wall and increases in magnitude with reductions in drag. Similarly, with increasing drag reduction, the profile of the combined Reynolds and polymer shear stress exhibits a decrease in its maximum value that also moves farther from the wall. Correlations are presented that estimate the location and value of the maximum rms streamwise velocity and combined Reynolds and polymer shear stress. Over the range of DR investigated, these effects consistently exhibit approximately linear trends as a function of DR. The present measurements allow reconstruction of the mean momentum balance (MMB) for channel flow, which provides further insights regarding the physics described in the study by White et al. In particular, the present findings support a physical scenario in which the self-similar properties on the inertial domain identified from the leading order structure of the MMB begin to detectably and continuously vary for drag reductions less than 10%.

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Section: Diagnostic Plotsupporting

confidence: 67%

Section: Diagnostic Plotmentioning

confidence: 91%

Turbulence Production in the Low Polymer Drag Reduction Regime

Elsnab

White

Klewicki

2019

Springer Proceedings in Physics

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“…Besides the established logarithmic behaviour for the mean velocity profile, recent data also support the existence of a logarithmic law for the streamwise velocity variance profile as predicted by the attached-eddy hypothesis [49]. Also higher-order even moments have been found to adhere to this scaling [7,50], although with some objections [8]. When it comes to the variance profile, the data are predicted, with increasing Re for a larger interior region, to follow )…”

Section: Reynolds Stresses (A) Streamwise Componentmentioning

confidence: 55%

“…Also higher-order even moments have been found to adhere to this scaling [7,50], although with some objections [8]. When it comes to the variance profile, the data are predicted, with increasing Re for a larger interior region, to follow y + /(R + ) 1/2 values of 2.6-3.9 [7,32,50]. It should be noted that, while the location of the lower bound for the logarithmic region in the aforementioned studies is found empirically, there is a physical basis, as argued by Klewicki and co-workers [52,53]: this position, in fact, should locate the start of the region where the mean dynamics lose a leading-order viscous effect.…”

Section: Reynolds Stresses (A) Streamwise Componentmentioning

confidence: 82%