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VOLUME 102 (2015) | ISSUE 11 |
PAGE 870
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Anisotropic characteristics of the Kraichnan direct cascade in two-dimensional hydrodynamic turbulence
E. A. Kuznetsov+*×, E. V. Sereshchenko+°∇
+Novosibirsk State University, 630090 Novosibirsk, Russia *Lebedev Physical Institute of the RAS, 119991 Moscow, Russia ×Landau Institute for Theoretical Physics of the RAS, 119334 Moscow, Russia °Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, 630090 Novosibirsk, Russia ∇Far-Eastern Federal University, 690091 Vladivostok, Russia
Abstract
Statistical characteristics of the Kraichnan direct cascade for
two-dimensional hydrodynamic turbulence
are numerically studied (with spatial resolution 8192× 8192) in the
presence of pumping and viscous-like
damping. It is shown that quasi-shocks of vorticity and their Fourier
partnerships in the form of jets introduce
an essential influence in turbulence leading to strong angular dependencies
for correlation functions. The energy
distribution as a function of modulus k for each angle in the inertial
interval has the Kraichnan behavior,
, and simultaneously a strong dependence on angles. However,
angle average provides with a high accuracy
the Kraichnan turbulence spectrum Ek=CKη2/3 k-3,
where η is
enstrophy flux and the Kraichnan
constant , in correspondence with the previous simulations.
Familiar situation takes place for third-order
velocity structure function S3L which, as for the isotropic turbulence,
gives the same scaling with respect to
separation length R and η, S3L=C3η R3, but the mean over
angles and time differs from its
isotropic value.
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