The contribution of kinetic helicity to turbulent magnetic diffusivity

Abstract

Using numerical simulations of forced turbulence, it is shown that for magnetic Reynolds numbers larger than unity, i.e., beyond the regime of quasilinear theory, the turbulent magnetic diffusivity attains an additional negative contribution that is quadratic in the kinetic helicity. In particular, for large magnetic Reynolds numbers, the turbulent magnetic diffusivity without helicity is about twice the value with helicity. Such a contribution was not previously anticipated, but, as we discuss, it turns out to be important when accurate estimates of the turbulent magnetic diffusivity are needed.

arXiv comment4 pages, 4 figures, Astron. Nachr., in press

References in corpus (16)

• The inverse cascade and nonlinear alpha-effect in simulations of isotropic helical hydromagnetic turbulence
• Mean-field concept and direct numerical simulations of rotating magnetoconvection and the geodynamo
• Magnetic diffusivity tensor and dynamo effects in rotating and shearing turbulence
• The Nuclear Stellar Disk in Andromeda: A Fossil from the Era of Black Hole Growth
• Kinematic alpha effect in isotropic turbulence simulations
• Scale dependence of alpha effect and turbulent diffusivity
• Nonlinear magnetic diffusivity and alpha tensors in helical turbulence
• Turbulence and its parameterization in accretion discs
• Contributions to the theory of a two-scale homogeneous dynamo experiment
• Dynamo coefficients from local simulations of the turbulent ISM
• Cosmic ray current-driven turbulence and mean-field dynamo effect
• Quenching and anisotropy of hydromagnetic turbulent transport
• Magnetic Fluctuations with a Zero Mean Field in a Random Fluid Flow with a Finite Correlation Time and a Small Magnetic Diffusion
• Mean-field effects in the Galloway-Proctor flow
• Calibrating passive scalar transport in shear-flow turbulence
• Mean-field diffusivities in passive scalar and magnetic transport in irrotational flows

Cited by in corpus (6)

• Advances in mean-field dynamo theory and applications to astrophysical turbulence
• Laminar and turbulent dynamos in chiral magnetohydrodynamics. II. Simulations
• Turbulent viscosity and effective magnetic Prandtl number from simulations of isotropically forced turbulence
• Path integrals for mean-field equations in nonlinear dynamos
• Helicity effect on turbulent passive and active scalar diffusivities
• Theory of the kinetic helicity effect on turbulent diffusion of magnetic and scalar fields