Scaling properties and intermittency of two-dimensional turbulence in pure electron plasmas

2013 ◽  
Vol 87 (6) ◽  
Author(s):  
F. Lepreti ◽  
M. Romé ◽  
G. Maero ◽  
B. Paroli ◽  
R. Pozzoli ◽  
...  
Keyword(s):  
Two Dimensional ◽  
Scaling Properties ◽  
Electron Plasmas

The scaling properties of two-dimensional compressible magnetohydrodynamic turbulence

2006 ◽  
Vol 13 (1) ◽  
pp. 012305 ◽  
Author(s):  
J. A. Merrifield ◽  
T. D. Arber ◽  
S. C. Chapman ◽  
R. O. Dendy
Keyword(s):  
Two Dimensional ◽  
Magnetohydrodynamic Turbulence ◽  
Scaling Properties

Algebraic probability density tails in decaying isotropic two-dimensional turbulence

1996 ◽  
Vol 313 ◽  
pp. 223-240 ◽  
Author(s):  
Javier Jiménez
Keyword(s):  
Isotropic Turbulence ◽  
Cauchy Distribution ◽  
Two Dimensional ◽  
Scaling Properties ◽  
Velocity Gradients ◽  
Random Arrangement ◽  
Coherent Vortices ◽  
Statistical Argument ◽  
Decaying Turbulence ◽  
The One

The p.d.f. of the velocity gradients in two-dimensional decaying isotropic turbulence is shown to approach a Cauchy distribution, with algebraic s−2 tails, as the flow becomes dominated by a large number of compact coherent vortices. The statistical argument is independent of the vortex structure, and depends only on general scaling properties. The same argument predicts a Gaussian p.d.f. for the velocity components. The convergence to these limits as a function of the number of vortices is analysed. It is found to be fast in the former case, but slow (logarithmic) in the latter, resulting in residual u−3 tails in all practical cases. The influence of a spread Gaussian vorticity distribution in the cores is estimated, and the relevant dimensionless parameter is identified as the area fraction covered by the cores. A comparison is made with the result of numerical simulations of two-dimensional decaying turbulence. The agreement of the p.d.f.s is excellent in the case of the gradients, and adequate in the case of the velocities. In the latter case the ratio between energy and enstrophy is computed, and agrees with the simulations. All the one-point statistics considered in this paper are consistent with a random arrangement of the vortex cores, with no evidence of energy screening.

SCALING PROPERTIES OF STRONG AVALANCHES IN SAND-PILE

2005 ◽  
Vol 16 (02) ◽  
pp. 341-348 ◽  
Author(s):  
A. B. SHAPOVAL ◽  
M. G. SHNIRMAN
Keyword(s):  
Power Function ◽  
The Other ◽  
Two Dimensional ◽  
Scaling Properties ◽  
Sand Pile

We introduced strong avalanches in the two-dimensional sand-pile and investigated the distributions F(·, L) of their size corresponding to the different system lengths L. Being appropriately scaled, these distributions coincide. The inverse map F-1as the function on L sets up the correspondence between the avalanches associated with different L. As to the strong avalanches, with any fixed first argument δ, the map F-1(δ, L) is proportional to a power function, where the exponent varies from 2 to 3 depending on δ, while F-1(δ, L) is proportional to L2for the other avalanches.

Scaling properties of two-dimensional turbulence in wakes behind bluff bodies

1997 ◽  
Vol 55 (4) ◽  
pp. 4165-4169 ◽  
Author(s):  
B. Protas ◽  
S. Goujon-Durand ◽  
J. E. Wesfreid
Keyword(s):  
Bluff Bodies ◽  
Two Dimensional ◽  
Scaling Properties

THE MULTIFRACTAL SCALING OF CLOUD RADIANCES FROM 1M TO 1KM

Fractals ◽  
2002 ◽  
Vol 10 (03) ◽  
pp. 253-264 ◽  
Author(s):  
D. SACHS ◽  
S. LOVEJOY ◽  
D. SCHERTZER
Keyword(s):  
Entire Range ◽  
Atmospheric Dynamics ◽  
Wave Number ◽  
Two Dimensional ◽  
Scale Invariant ◽  
Spectral Exponent ◽  
Scaling Properties ◽  
Anisotropic Scaling ◽  
Multifractal Scaling ◽  
Cloud Thickness

The cloud radiances and atmospheric dynamics are strongly nonlinearly coupled, the observed scaling of the former from 1 km to planetary scales is prima facae evidence for scale invariant dynamics. In contrast, the scaling properties of radiances at scales <1 km have not been well studied (contradictory claims have been made) and if a characteristic vertical cloud thickness existed, it could break the scaling of the horizontal radiances. In order to settle this issue, we use ground-based photography to study the cloud radiance field through the range scales where breaks in scaling have been reported (30 m to 500 m). Over the entire range 1 m to 1 km the two-dimensional (2D) energy spectrum (E(k)) of 38 clouds was found to accurately follow the scaling form E(k)≈ k-β where k is a wave number and β is the spectral exponent. This indirectly shows that there is no characteristic vertical cloud thickness, and that "radiative smoothing" of cloud structures occurs at all scales. We also quantitatively characterize the type of (multifractal) scaling showing that the main difference between transmitted and reflected radiance fields is the (scale-by-scale) non-conservation parameter H. These findings lend support to the unified scaling model of the atmosphere which postulates a single anisotropic scaling regime from planetary down to dissipation scales.

Dynamics and scaling properties of localization in energy space in two-dimensional mesoscopic systems

1992 ◽  
Vol 46 (12) ◽  
pp. 7691-7706 ◽  
Author(s):  
Yuval Gefen ◽  
Dror Lubin ◽  
Isaac Goldhirsch
Keyword(s):  
Energy Space ◽  
Two Dimensional ◽  
Mesoscopic Systems ◽  
Scaling Properties

Quantitative three-dimensional imaging and the structure of passive scalar fields in fully turbulent flows

1990 ◽  
Vol 216 ◽  
pp. 1-34 ◽  
Author(s):  
Rahul R. Prasad ◽  
K. R. Sreenivasan
Keyword(s):  
Turbulent Flows ◽  
Three Dimensional ◽  
Scalar Fields ◽  
Passive Scalar ◽  
Working Fluid ◽  
Small Scale ◽  
Main Body ◽  
Two Dimensional ◽  
Scaling Properties ◽  
Two Dimensional Images

The three-dimensional turbulent field of a passive scalar has been mapped quantitatively by obtaining, effectively instantaneously, several closely spaced parallel two-dimensional images; the two-dimensional images themselves have been obtained by laser-induced fluorescence. Turbulent jets and wakes at moderate Reynolds numbers are used as examples. The working fluid is water. The spatial resolution of the measurements is about four Kolmogorov scales. The first contribution of this work concerns the three-dimensional nature of the boundary of the scalar-marked regions (the ‘scalar interface’). It is concluded that interface regions detached from the main body are exceptional occurrences (if at all), and that in spite of the large structure, the randomness associated with small-scale convolutions of the interface are strong enough that any two intersections of it by parallel planes are essentially uncorrelated even if the separation distances are no more than a few Kolmogorov scales. The fractal dimension of the interface is determined directly by box-counting in three dimensions, and the value of 2.35 ± 0.04 is shown to be in good agreement with that previously inferred from two-dimensional sections. This justifies the use of the method of intersections. The second contribution involves the joint statistics of the scalar field and the quantity χ* (or its components), χ* being the appropriate approximation to the scalar ‘dissipation’ field in the inertial–convective range of scales. The third aspect relates to the multifractal scaling properties of the spatial intermittency of χ*; since all three components of χ* have been obtained effectively simultaneously, inferences concerning the scaling properties of the individual components and their sum have been possible. The usefulness of the multifractal approach for describing highly intermittent distributions of χ* and its components is explored by measuring the so-called singularity spectrum (or the f(α)-curve) which quantifies the spatial distribution of various strengths of χ*. Also obtained is a time sequence of two-dimensional images with the temporal resolution on the order of a few Batchelor timescales; this enables us to infer features of temporal intermittency in turbulent flows, and qualitatively the propagation speeds of the scalar interface. Finally, a few issues relating to the resolution effects have been addressed briefly by making point measurements with the spatial and temporal resolutions comparable with the Batchelor lengthscale and the corresponding timescale.

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