Logarithmic violation of scaling in strongly anisotropic turbulent transfer of a passive vector field

Abstract

Inertial-range asymptotic behavior of a vector (e.g., magnetic) field, passively advected by a strongly anisotropic turbulent flow, is studied by means of the field theoretic renormalization group and the operator product expansion. The advecting velocity field is Gaussian, not correlated in time, with the pair correlation function of the form $\propto \delta (t-t^{\prime })/k_{\perp }^{d-1+\xi }$, where $k_{\perp }=|{\mathbf{k}}_{\perp }|$ and ${\mathbf{k}}_{\perp }$ is the component of the wave vector, perpendicular to the distinguished direction (`direction of the flow') -- the $d$-dimensional generalization of the ensemble introduced by Avellaneda and Majda [{\it Commun. Math. Phys.} {\bf 131}: 381 (1990)]. The stochastic advection-diffusion equation for the transverse (divergence-free) vector field includes, as special cases, the kinematic dynamo model for magnetohydrodynamic turbulence and the linearized Navier--Stokes equation. In contrast to the well known isotropic Kraichnan's model, where various correlation functions exhibit anomalous scaling behavior with infinite sets of anomalous exponents, here the dependence on the integral turbulence scale $L$ has a logarithmic behavior: instead of power-like corrections to ordinary scaling, determined by naive (canonical) dimensions, the anomalies manifest themselves as polynomials of logarithms of $L$. The key point is that the matrices of scaling dimensions of the relevant families of composite operators appear nilpotent and cannot be diagonalized. The detailed proof of this fact is given for correlation functions of arbitrary order.

30 pages, LaTeX source, 7 eps figures. Extended version: new abstracts A and B, numerous minor improvements in text

References in corpus (4)

• Anomalous scaling and large-scale anisotropy in magnetohydrodynamic turbulence: Two-loop renormalization-group analysis of the Kazantsev--Kraichnan kinematic model
• Dynamo effect in the Kraichnan magnetohydrodynamic turbulence
• Anomalous scaling of a passive scalar advected by the turbulent velocity field with finite correlation time and uniaxial small-scale anisotropy
• Anomalous scaling of a passive vector field in $d$ dimensions: Higher-order structure functions

Cited by in corpus (4)

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• Stochastic Navier-Stokes equation and advection of a tracer field: One-loop renormalization near $d=4$
• Dimensional transmutation and nonconventional scaling behaviour in a model of self-organized criticality