95 research outputs found
Lagrangian and Eulerian velocity structure functions in hydrodynamic turbulence
The Lagrangian and Eulerian transversal velocity structure functions of fully
developed fluid turbulence are found basing on the Navier-Stokes equation. The
structure functions are shown to obey the scaling relations inside the inertial
range. The scaling exponents are calculated analytically without using
dimensional considerations. The obtained values are in a very good agreement
with recent numerical and experimental data.Comment: 4 pages, 1 figur
Evolution of localized magnetic field perturbations and the nature of turbulent dynamo
Kinematic dynamo in incompressible isotropic turbulent flows with high
magnetic Prandtl number is considered. The approach interpreting an arbitrary
magnetic field distribution as a superposition of localized perturbations
(blobs) is proposed. We derive a relation between stochastic properties of a
blob and a stochastically homogenous distribution of magnetic field advected by
the same stochastic flow. This relation allows to investigate the evolution of
a localized blob at late stage when its size exceeds the viscous scale. It is
shown that in 3-dimansional flows, the average magnetic field of the blob
increases exponentially in the inertial range of turbulence, as opposed to the
late-Batchelor stage when it decreases. Our approach reveals the mechanism of
dynamo generation in the inertial range both for blobs and homogenous
contributions. It explains the absence of dynamo in the two-dimensional case
and its efficiency in three dimensions. We propose the way to observe the
mechanism in numerical simulations.Comment: 10 pages, 1 figur
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