1,461 research outputs found
Multiscale self-organized criticality and powerful X-ray flares
A combination of spectral and moments analysis of the continuous X-ray flux
data is used to show consistency of statistical properties of the powerful
solar flares with 2D BTW prototype model of self-organized criticality
Logarithmic scaling in the near-dissipation range of turbulence
A logarithmic scaling for structure functions, in the form , where is the Kolmogorov dissipation scale and
are the scaling exponents, is suggested for the statistical
description of the near-dissipation range for which classical power-law scaling
does not apply. From experimental data at moderate Reynolds numbers, it is
shown that the logarithmic scaling, deduced from general considerations for the
near-dissipation range, covers almost the entire range of scales (about two
decades) of structure functions, for both velocity and passive scalar fields.
This new scaling requires two empirical constants, just as the classical
scaling does, and can be considered the basis for extended self-similarity
Very fine structures in scalar mixing
We explore very fine scales of scalar dissipation in turbulent mixing, below
Kolmogorov and around Batchelor scales, by performing direct numerical
simulations at much finer grid resolution than is usually adopted in the past.
We consider the resolution in terms of a local, fluctuating Batchelor scale and
study the effects on the tails of the probability density function and
multifractal properties of the scalar dissipation. The origin and importance of
these very fine-scale fluctuations are discussed. One conclusion is that they
are unlikely to be related to the most intense dissipation events.Comment: 10 pages, 7 figures (low quality due to downsizing
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