TY - JOUR
T1 - The contribution of kinetic helicity to turbulent magnetic diffusivity
AU - Brandenburg, A.
AU - Schober, J.
AU - Rogachevskii, I.
N1 - Funding Information: NSF Astrophysics and Astronomy Grant Program, 1615100. Research Council of Norway, FRINATEK 231444. National Science Foundation, CNS-0821794. University of Colorado Boulder. University of Colorado Denver. National Center for Atmospheric Research. Funding Information: Support through the NSF Astrophysics and Astronomy Grant Program (grant 1615100), and the Research Council of Norway (FRINATEK grant 231444), are gratefully acknowledged. We acknowledge the allocation of computing resources provided by the Swedish National Allocations Committee at the Center for Parallel Computers at the Royal Institute of Technology in Stockholm. This work utilized the Janus supercomputer, which is supported by the National Science Foundation (award number CNS-0821794), the University of Colorado Boulder, the University of Colorado Denver, and the National Center for Atmospheric Research. The Janus supercomputer is operated by the University of Colorado, Boulder. Publisher Copyright: © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2017/8/1
Y1 - 2017/8/1
N2 - Using numerical simulations of forced turbulence, we show that for magnetic Reynolds numbers larger than unity, that is, 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.
AB - Using numerical simulations of forced turbulence, we show that for magnetic Reynolds numbers larger than unity, that is, 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.
KW - magnetic fields
KW - magnetohydrodynamics (MHD)
KW - turbulence
UR - http://www.scopus.com/inward/record.url?scp=85030245807&partnerID=8YFLogxK
U2 - https://doi.org/10.1002/asna.201713384
DO - https://doi.org/10.1002/asna.201713384
M3 - Article
SN - 0004-6337
VL - 338
SP - 790
EP - 793
JO - Astronomische Nachrichten
JF - Astronomische Nachrichten
IS - 7
ER -