Velocity and temperature derivatives in high Reynolds number turbulent flows in the atmospheric surface layer

2008 ◽  
pp. 462-464
Author(s):  
G. Gulitski ◽  
M. Kholmyansky ◽  
W. Kinzelbach ◽  
B. Lüthi ◽  
A. Tsinober ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Surface Layer ◽  
Turbulent Flows ◽  
High Reynolds Number ◽  
Atmospheric Surface Layer ◽  
High Reynolds

scholarly journals Velocity and temperature derivatives in high-Reynolds-number turbulent flows in the atmospheric surface layer. Part 1. Facilities, methods and some general results

2007 ◽  
Vol 589 ◽  
pp. 57-81 ◽  
Author(s):  
G. GULITSKI ◽  
M. KHOLMYANSKY ◽  
W. KINZELBACH ◽  
B. LÜTHI ◽  
A. TSINOBER ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Surface Layer ◽  
Turbulent Flows ◽  
Atmospheric Surface Layer ◽  
Stokes Equations ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Taylor Hypothesis ◽  
High Reynolds

This is a report on a field experiment in an atmospheric surface layer at heights between 0.8 and 10m with the Taylor micro-scale Reynolds number in the range Reλ = 1.6−6.6 ×103. Explicit information is obtained on the full set of velocity and temperature derivatives both spatial and temporal, i.e. no use of Taylor hypothesis is made. The report consists of three parts. Part 1 is devoted to the description of facilities, methods and some general results. Certain results are similar to those reported before and give us confidence in both old and new data, since this is the first repetition of this kind of experiment at better data quality. Other results were not obtained before, the typical example being the so-called tear-drop R-Q plot and several others. Part 2 concerns accelerations and related matters. Part 3 is devoted to issues concerning temperature, with the emphasis on joint statistics of temperature and velocity derivatives. The results obtained in this work are similar to those obtained in experiments in laboratory turbulent grid flow and in direct numerical simulations of Navier–Stokes equations at much smaller Reynolds numbers Reλ ~ 102, and this similarity is not only qualitative, but to a large extent quantitative. This is true of such basic processes as enstrophy and strain production, geometrical statistics, the role of concentrated vorticity and strain, reduction of nonlinearity and non-local effects. The present experiments went far beyond the previous ones in two main respects. (i) All the data were obtained without invoking the Taylor hypothesis, and therefore a variety of results on fluid particle accelerations became possible. (ii) Simultaneous measurements of temperature and its gradients with the emphasis on joint statistics of temperature and velocity derivatives. These are reported in Parts 2 and 3.

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.

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.

Low-Dimensional Tools for Closed-Loop Flow-Control in High Reynolds Number Turbulent Flows

2008 ◽  
pp. 293-310 ◽  
Author(s):  
Joseph W. Hall ◽  
Charles E. Tinney ◽  
Julie M. Ausseur ◽  
Jeremy T. Pinier ◽  
Andre M. Hall ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Flow Control ◽  
Turbulent Flows ◽  
High Reynolds Number ◽  
Closed Loop ◽  
High Reynolds ◽  
Low Dimensional

scholarly journals The emergence of localized vortex–wave interaction states in plane Couette flow

2013 ◽  
Vol 721 ◽  
pp. 58-85 ◽  
Author(s):  
Kengo Deguchi ◽  
Philip Hall ◽  
Andrew Walton
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
High Reynolds Number ◽  
Stokes Equations ◽  
Wave Interaction ◽  
Critical Layer ◽  
Navier Stokes ◽  
Turbulent Spots ◽  
Navier Stokes Equations ◽  
High Reynolds

AbstractThe recently understood relationship between high-Reynolds-number vortex–wave interaction theory and computationally generated self-sustaining processes provides a possible route to an understanding of some of the underlying structures of fully turbulent flows. Here vortex–wave interaction (VWI) theory is used in the long streamwise wavelength limit to continue the development found at order-one wavelengths by Hall & Sherwin (J. Fluid Mech., vol. 661, 2010, pp. 178–205). The asymptotic description given reduces the Navier–Stokes equations to the so-called boundary-region equations, for which we find equilibrium states describing the change in the VWI as the wavelength of the wave increases from $O(h)$ to $O(Rh)$, where $R$ is the Reynolds number and $2h$ is the depth of the channel. The reduced equations do not include the streamwise pressure gradient of the perturbation or the effect of streamwise diffusion of the wave–vortex states. The solutions we calculate have an asymptotic error proportional to ${R}^{- 2} $ when compared to the full Navier–Stokes equations. The results found correspond to the minimum drag configuration for VWI states and might therefore be of relevance to the control of turbulent flows. The key feature of the new states discussed here is the thickening of the critical layer structure associated with the wave part of the flow to completely fill the channel, so that the roll part of the flow is driven throughout the flow rather than as in Hall & Sherwin as a stress discontinuity across the critical layer. We identify a critical streamwise wavenumber scaling, which, when approached, causes the flow to localize and take on similarities with computationally generated or experimentally observed turbulent spots. In effect, the identification of this critical wavenumber for a given value of the assumed high Reynolds number fixes a minimum box length necessary for the emergence of localized structures. Whereas nonlinear equilibrium states of the Navier–Stokes equations are thought to form a backbone on which turbulent flows hang, our results suggest that the localized states found here might play a related role for turbulent spots.

scholarly journals High-Reynolds-number weakly stratified flow past an obstacle

1996 ◽  
Vol 317 ◽  
pp. 155-178 ◽  
Author(s):  
S. I. Chernyshenko ◽  
Ian P. Castro
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
Turbulent Flows ◽  
High Reynolds Number ◽  
Bluff Body ◽  
Physical Mechanisms ◽  
Flow Past ◽  
Large Channel ◽  
Weak Stratification ◽  
High Reynolds

Stably stratified steady flow past a bluff body in a channel is considered for cases in which the stratification is not sufficiently strong to give solutions containing wave motions. The physical mechanisms by which stratification influences the flow are revealed. In particular, the drag reduction under weak stratification, observed in experiments, is explained. This is achieved by constructing an asymptotic laminar solution for high Reynolds number (Re) and large channel width, which explicitly gives the mechanisms, and using comparisons with numerical results for medium Re and experiments for turbulent flows to argue that these mechanisms are expected to be common in all cases. The results demonstrate the possibility, subject to certain restrictions, of using steady high-Re theory as a tool for studying qualitative features of real flows.

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