High Reynolds Number [Rθ=O(106)] Boundary Layer Turbulence in the Atmospheric Surface Layer Above Western Utah’s Salt Flats

1998 ◽  
pp. 450-466 ◽  
Author(s):  
J. C. Klewicki ◽  
J. F. Foss ◽  
J. M. Wallace
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Surface Layer ◽  
High Reynolds Number ◽  
Atmospheric Surface Layer ◽  
Boundary Layer Turbulence ◽  
Salt Flats ◽  
High Reynolds

scholarly journals Interactions within the turbulent boundary layer at high Reynolds number

2011 ◽  
Vol 666 ◽  
pp. 573-604 ◽  
Author(s):  
M. GUALA ◽  
M. METZGER ◽  
B. J. McKEON
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Surface Layer ◽  
High Reynolds Number ◽  
Large Scale ◽  
Atmospheric Surface Layer ◽  
Vertical Direction ◽  
Wall Region ◽  
High Reynolds ◽  
Near Wall

Simultaneous streamwise velocity measurements across the vertical direction obtained in the atmospheric surface layer (Reτ ≃ 5 × 105) under near thermally neutral conditions are used to outline and quantify interactions between the scales of turbulence, from the very-large-scale motions to the dissipative scales. Results from conditioned spectra, joint probability density functions and conditional averages show that the signature of very-large-scale oscillations can be found across the whole wall region and that these scales interact with the near-wall turbulence from the energy-containing eddies to the dissipative scales, most strongly in a layer close to the wall, z+ ≲ 103. The scale separation achievable in the atmospheric surface layer appears to be a key difference from the low-Reynolds-number picture, in which structures attached to the wall are known to extend through the full wall-normal extent of the boundary layer. A phenomenological picture of very-large-scale motions coexisting and interacting with structures from the hairpin paradigm is provided here for the high-Reynolds-number case. In particular, it is inferred that the hairpin-packet conceptual model may not be exhaustively representative of the whole wall region, but only of a near-wall layer of z+ = O(103), where scale interactions are mostly confined.

Well Resolved Wall Pressure Measurements in a High Reynolds Number Turbulent Boundary Layer

2004 ◽  
Author(s):  
Brendan F. Perkins
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Surface Pressure ◽  
High Reynolds Number ◽  
Wall Pressure ◽  
Pressure Measurements ◽  
Boundary Layer Turbulence ◽  
High Reynolds ◽  
Salt Playa

In order to better understand boundary layer turbulence at high Reynolds number, the fluctuating wall pressure was measured within the turbulent boundary layer that forms over the salt playa of Utah’s west desert. Pressure measurements simultaneously acquired from an array of nine microphones were analyzed and interpreted. The wall pressure intensity was computed and compared with low Reynolds number data. This analysis indicated that the variance in wall pressure increases logarithmically with Reynolds number. Computed autocorrelations provide evidence for a hierarchy of surface pressure producing scales. Space-time correlations are used to compute broadband convection velocities. The convection velocity data indicate an increasing value for larger sensor separations. To the author’s knowledge, the pressure measurements are the highest Reynolds number, well resolved measurements of fluctuating surface pressure to date.

The near-neutral atmospheric surface layer: turbulence and non-stationarity

2007 ◽  
Vol 365 (1852) ◽  
pp. 859-876 ◽  
Author(s):  
M Metzger ◽  
B.J McKeon ◽  
H Holmes
Keyword(s):  
Reynolds Number ◽  
Surface Layer ◽  
Thermal Stratification ◽  
High Reynolds Number ◽  
Atmospheric Surface Layer ◽  
Western Desert ◽  
Hot Wire ◽  
Velocity Statistics ◽  
High Reynolds ◽  
Very High

The neutrally stable atmospheric surface layer is used as a physical model of a very high Reynolds number, canonical turbulent boundary layer. Challenges and limitations with this model are addressed in detail, including the inherent thermal stratification, surface roughness and non-stationarity of the atmosphere. Concurrent hot-wire and sonic anemometry data acquired in Utah's western desert provide insight to Reynolds number trends in the axial velocity statistics and spectra.

Characterization of the Custom-Designed, High Reynolds Number Water Tunnel

2016 ◽  
Author(s):  
Yasaman Farsiani ◽  
Brian R. Elbing
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Test Section ◽  
High Reynolds Number ◽  
Layer Growth ◽  
Water Tunnel ◽  
Freestream Velocity ◽  
Section Design ◽  
High Reynolds

This paper reports on the characterization of the custom-designed high-Reynolds number recirculating water tunnel located at Oklahoma State University. The characterization includes the verification of the test section design, pump calibration and the velocity distribution within the test section. This includes an assessment of the boundary layer growth within the test section. The tunnel was designed to achieve a downstream distance based Reynolds number of 10 million, provide optical access for flow visualization and minimize inlet flow non-uniformity. The test section is 1 m long with 15.2 cm (6-inch) square cross section and acrylic walls to allow direct line of sight at the tunnel walls. The verification of the test section design was accomplished by comparing the flow quality at different location downstream of the flow inlet. The pump was calibrated with the freestream velocity with three pump frequencies and velocity profiles were measured at defined locations for three pump speeds. Boundary layer thicknesses were measured from velocity profile results and compared with analytical calculations. These measurements were also compared against the facility design calculations.

scholarly journals Wall-attached structures of velocity fluctuations in a turbulent boundary layer

2018 ◽  
Vol 856 ◽  
pp. 958-983 ◽  
Author(s):  
Jinyul Hwang ◽  
Hyung Jin Sung
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
High Reynolds Number ◽  
Wall Turbulence ◽  
Velocity Fluctuations ◽  
Moderate Reynolds Number ◽  
Wide Range ◽  
Logarithmic Region ◽  
High Reynolds ◽  
Attached Eddies

Wall turbulence is a ubiquitous phenomenon in nature and engineering applications, yet predicting such turbulence is difficult due to its complexity. High-Reynolds-number turbulence arises in most practical flows, and is particularly complicated because of its wide range of scales. Although the attached-eddy hypothesis postulated by Townsend can be used to predict turbulence intensities and serves as a unified theory for the asymptotic behaviours of turbulence, the presence of coherent structures that contribute to the logarithmic behaviours has not been observed in instantaneous flow fields. Here, we demonstrate the logarithmic region of the turbulence intensity by identifying wall-attached structures of the velocity fluctuations ($u_{i}$) through the direct numerical simulation of a moderate-Reynolds-number boundary layer ($Re_{\unicode[STIX]{x1D70F}}\approx 1000$). The wall-attached structures are self-similar with respect to their heights ($l_{y}$), and in particular the population density of the streamwise component ($u$) scales inversely with $l_{y}$, reminiscent of the hierarchy of attached eddies. The turbulence intensities contained within the wall-parallel components ($u$ and $w$) exhibit the logarithmic behaviour. The tall attached structures ($l_{y}^{+}>100$) of $u$ are composed of multiple uniform momentum zones (UMZs) with long streamwise extents, whereas those of the cross-stream components ($v$ and $w$) are relatively short with a comparable width, suggesting the presence of tall vortical structures associated with multiple UMZs. The magnitude of the near-wall peak observed in the streamwise turbulent intensity increases with increasing $l_{y}$, reflecting the nested hierarchies of the attached $u$ structures. These findings suggest that the identified structures are prime candidates for Townsend’s attached-eddy hypothesis and that they can serve as cornerstones for understanding the multiscale phenomena of high-Reynolds-number boundary layers.

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