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| Titel |
Solar wind low-frequency magnetohydrodynamic turbulence: extended self-similarity and scaling laws |
| VerfasserIn |
V. Carbone, P. Veltri, R. Bruno |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 3, no. 4 ; Nr. 3, no. 4, S.247-261 |
| Datensatznummer |
250001123
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| Publikation (Nr.) |
 copernicus.org/npg-3-247-1996.pdf |
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| Zusammenfassung |
| In this paper we review some of the
work done in
investigating the scaling properties of
Magnetohydrodynamic
turbulence, by using velocity fluctuations
measurements
performed in the interplanetary space plasma by the
Helios
spacecraft. The set of scaling exponents ξq
for the q-th
order velocity structure functions, have been
determined by
using the Extended Self-Similarity hypothesis. We have
found
that the q-th order velocity structure function,
when plotted
vs. the 4-th order structure function, displays a
range of
self-similarity which extends over all the lengths
covered by
measurements, thus allowing for a very good
determination of ξq. Moreover the results seem to
show that the scaling
exponents are the same regardless the various
observation
periods considered. The obtained scaling exponents
have been
compared with the results of some intermittency
models for
Kraichnan's turbulence, derived in the framework of
infinitely
divisible fragmentation processes, showing the good
agreement
between these models and our observations. Finally,
on the
basis of the actually available data sets, we
show that
scaling laws in Solar Wind turbulence seem to be
different
from turbulent scaling laws in the ordinary fluid
flows. This
is true for high-order velocity structure
functions, while
low-order velocity structure functions show the same
scaling
laws. Since our measurements involve length scales
which
extend over many order of magnitude where
dissipation is
practically absent, our results show that Solar
Wind
turbulence can be regarded as a testing bench
for the
investigation of general scaling behaviour in turbulent
flows.
In particular our results strongly support the point
of view
which attributes a key role to the inertial range
dynamics in
determining the intermittency characteristics in fluid
flows,
in contrast with the point of view which
attributes
intermittency to a finite Reynolds number effect. |
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