Examples of turbulence

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An analogy with the dynamics of an isotropic, inertial subrange in three-dimensional turbulence should be noted.
The increase in lateral contact creates a constriction that narrows the air channel and produces an automatic turbulence noise, leading to an affricated release.
The generation of sheared (zonal) flows by drift-wave turbulence is by now part of the standard paradigm [98].
The fluctuations grow exponentially at first and develop into turbulence without being accompanied by abrupt bursts or turbulent spots.
The predicted turbulence intensities are shown in figures 5(b)-5(e).
The mean flow and turbulence behaviour in the curved-wall and flat-plate experiments was qualitatively similar.
The generation of large-scale zonal flows by small-scale electrostatic drift waves in electron temperature gradient driven turbulence model is considered.
Exclusive dependence of the interpolation parameter on the mean strain and rotation invariants is deemed unphysical, for they contain no indication of the turbulence state.
The turbulence physics appears to vary smoothly between the different extremes.
The flow structure of the combined jet exhibits all characteristics of a single-jet flow except for an altered evolution of the turbulence toward self-preservation.
In this reviewer's view, it constitutes a worthy addition to the literature on the technologically and scientifically important fields of fluid and plasma turbulence.
In either figure, there is a conspicuous concentration of turbulence production in a small region close to and ahead of the thin vortex core.
The water was fed to the stagnation chamber through a perforated pipe located upstream of two turbulence-reducing screens.
Quantitative results are obtained for the increased heat transfer to the toroidal walls due to turbulence as well as radial profiles for the transport coefficients.
A word of caution is appropriate however since the turbulence characteristics of jets are more non-homogeneous than the characteristics of wakes.
The observed similarity of edge turbulence in limited and diverted geometries motivates a search for universal mechanisms.
Transport of energy and particles across flux surfaces in tokamaks and optimized stellarators is largely determined by drift wave turbulence.
We investigate particle acceleration by strong lower-hybrid turbulence produced by the relaxation of an energetic perpendicular ion ring distribution.
Thus negative production - which contradicts gradient transport hypotheses and turbulence modelling theories - can be explained by coherent structure motions and their interactions.
Reduction of jet noise through turbulence suppression is one.
Chapter 4 takes up the important practical matter of turbulence modelling.
The ordinate has been normalized by the large-scale turbulence integral lengthscale at the source (table 1).
Many experiments have been devoted to the time history of homogeneous, isotropic turbulence produced by a grid in uniform flow wind tunnels under neutral conditions.
The intensified turbulence concentrated at these scales is the agent causing the observed increases in shear stress and heat transfer at the wall.
The general theory was applied to the case of a free jet along which turbulence is convected.
The theory is based on the assumption that the radiation is purely a byproduct of the turbulence.
The turbulence was then maintained by the flow as assumed by the theory.
The initial turbulence was in all cases derived from nozzle wall roughness.
We also obtain some important new results for small-scale turbulence by expanding the solutions in inverse powers of the turbulence spatial scale.
Here, the possibility will be examined, that the rapid-distortion equations can be used to calculate stress ratios for finite general distortions of sheared turbulence.
Here the mixing of the reactants is solely determined by the turbulence - turbulence interactions.
Here the median and peak of the temperature distribution are deflected towards the largescale turbulence region.
The importa.nce of this direction of turbulence research will be emphasized again at the conclusion of this paper.
From a mathematical point of view, turbulence theory is embedded in the theory of approximation of functional-differential equations.
The theory may be reformulated for turbulence in which there is non-zero mean velocity.
Figure 7 (a)shows a segment of computer-generated turbulence.
The last of these states that, on the average, the background turbulence and the organized motion are uncorrelated.
Indeed, this mechanism may contribute to the very marked turbulence that is present in all waves under the action of wind.
Therefore, since the uncertainty in u, is small, these results are believed to accurately represent the turbulence structure.
The behaviour of small-scale turbulence undergoing distortion was found to differ drastically from that of large-scale turbulence.
Since the turbulence is also very nearly self-similar, this location is by no means special, but is representative of the entire shear layer.
What is missing in this hypothesis is an actual instability mechanism for the production of streamwise vorticity and the subsequent breakdown to small-scale turbulence.
From left to right the bracketed groups of terms represent advection, production, diffusion and dissipation of turbulence energy.
They were concerned primarily with the turbulence energy generation in the mean shear region at the interface between the fluid streams.
The diffusion and dissipation terms of the turbulence kinetic energy equation could not be estimated directly.
Turbulence in stratified media is a phenomenon common t o a variety of geophysical and engineering situations.
To capture the behaviour of complex flows, the model coefficients must be functions of the imposed deformation rate and the state of turbulence.
All the turbulence state variables at equilibrium are completely determined by mean flow deformation.
We have already established that the new model performs very well in homogeneous turbulence.
In relation to the present model, the smaller nozzles establish smaller turbulence scales that effectively suppress the generation of large-scale turbulence (instabilities).
He also obtained an approximate solution for the effective eddy viscosity in the viscous limit (fast turbulence relaxation).
There, the main physical process is intrinsically the same as the one that characterized the transition from laminarity to turbulence.
The geometries are different, but the averaged equations are nearly the same, differing only in the turbulence and viscous transport terms.
A transport equation can carry turbulence energy outside the regions of strong shear towards the centre of the domain.
Both the mean flow and the turbulence were strongly affected by the pressure gradient.
In the implicit approach, the compressibility is assumed to influence the structure of the turbulence and this in turn changes the turbulence energetics.
The turbulence intensity 4" and shear-stress r appear to grow too rapidly into the outer layers when plotted against, distance from the wall.
The correlations are probably detecting the weakened remnants of the structure entering the bend, and this only because the background turbulence level is quite low.
In rapid distortion by shear, the turbulence is non-stationary, and dominated by vorticity tilting and stretching.
Indirectly, the dissipation profile near a free surface promotes surface renewal by increasing the value of the turbulence velocity scale there.
The question of the site and magnitude of the turbulence production is also left under a small cloud.
The program used in these predictions contains a one-equation model of turbulence, using turbulence kinetic energy with an algebraic mixing length.
The comparison of visualization and anemometry has helped to emphasize that turbulence is by nature three-dimensional.
However, to date, there is no evidence of loss of regularity in the physics of turbulence between the rapid distortion state and equilibrium.
The intermediate states of turbulence are more difficult to analyse because of the complex interplay among the various competing processes.
In order to build an 'optimal' turbulence model, which incorporates all the above features, a two-step methodology is proposed.
Many aspects of turbulence in equilibrium are understood from laboratory and numerical experiments.
The flows analyzed in this paper are simple but representative examples of turbulence in the vicinity of solid boundaries.
The shock-foot region is a source of turbulence production and of enhanced compressibility effects, which are expressed by an increased pressure dilatation.
At the immediate follow-up, turbulences were noted in the area of the device (nine cases) and in the left pulmonary artery (seven cases).
Under the seemingly stable surface of iron control, there exist dynamic turbulences of conflict, repression, resistance, competition, compromise, and co-operation in which law, power and politics are interacting.
Both were created at times of great turbulence, as the old orders were crushed.
The model predictions are very sensitive to the turbulence of the atmosphere, which is inherently difficult to measure or predict.
Rather, words such as "turbulence" or "spatialtemporal chaos" may be more appropriate.
The ice cover inhibits wind-induced turbulence, minimizes penetration of sunlight and keeps the temperature of the surface waters almost constant.
In the wake of this phenomenon, books addressing the complexities and emotional turbulence of the process of transracial adoption have started to appear with frequency.
Such expectations are not always fulfilled; but, when they fail, this may itself be informative about the structure of the turbulence.
Here, without detail, we use the context of homogeneous isotropic turbulence to develop some ideas relevant to all turbulent flows.
In particular, one wants to understand the way in which the turbulence spreads.
There is little interaction between the turbulence and the mean flow in the intervals between eruptions and inrushes.
The turbulence is being kept going by the working of this against the mean velocity gradient.
A complete specification of the turbulence again requires one to consider all orders up to infinity.
The localized regions of turbulence are known as turbulent spots.
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