Scale Locality of Magnetohydrodynamic Turbulence

Hussein Aluie and Gregory L. Eyink
Phys. Rev. Lett. 104, 081101 – Published 26 February 2010

Abstract

We investigate the scale locality of cascades of conserved invariants at high kinetic and magnetic Reynold’s numbers in the “inertial-inductive range” of magnetohydrodynamic (MHD) turbulence, where velocity and magnetic field increments exhibit suitable power-law scaling. We prove that fluxes of total energy and cross helicity—or, equivalently, fluxes of Elsässer energies—are dominated by the contributions of local triads. Flux of magnetic helicity may be dominated by nonlocal triads. The magnetic stretching term may also be dominated by nonlocal triads, but we prove that it can convert energy only between velocity and magnetic modes at comparable scales. We explain the disagreement with numerical studies that have claimed conversion nonlocally between disparate scales. We present supporting data from a 10243 simulation of forced MHD turbulence.

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  • Received 22 September 2009

DOI:https://doi.org/10.1103/PhysRevLett.104.081101

©2010 American Physical Society

Authors & Affiliations

Hussein Aluie1,2 and Gregory L. Eyink1

  • 1The Johns Hopkins University, Applied Mathematics & Statistics, Baltimore, Maryland 21218, USA
  • 2Theoretical Division (T-5/CNLS), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

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Issue

Vol. 104, Iss. 8 — 26 February 2010

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