Energetics of turbulence generated by chiral MHD dynamos

J. Schober, A. Brandenburg, I. Rogachevskii, N. Kleeorin

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


An asymmetry in the number density of left- and right-handed fermions is known to give rise to a new term in the induction equation that can result in a dynamo instability. At high temperatures, when a chiral asymmetry can survive for long enough, this chiral dynamo instability can amplify magnetic fields efficiently, which in turn drive turbulence via the Lorentz force. While it has been demonstrated in numerical simulations that this chiral magnetically driven turbulence exists and strongly affects the dynamics of the magnetic field, the details of this process remain unclear. The goal of this paper is to analyse the energetics of chiral magnetically driven turbulence and its effect on the generation and dynamics of the magnetic field using direct numerical simulations. We study these effects for different initial conditions, including a variation of the initial chiral chemical potential and the magnetic Prandtl number, PrM. In particular, we determine the ratio of kinetic to magnetic energy, Υ, in chiral magnetically driven turbulence. Within the parameter space explored in this study, Υ reaches a value of approximately 0.064–0.074–independently of the initial chiral asymmetry and for PrM = 1. Our simulations suggest, that Υ decreases as a power law when increasing PrM by decreasing the viscosity. While the exact scaling depends on the details of the fitting criteria and the Reynolds number regime, an approximate result of Υ(PrM)=0.1 Pr-0.4M is reported. Using the findings from our numerical simulations, we analyse the energetics of chiral magnetically driven turbulence in the early Universe.

Original languageEnglish
Pages (from-to)107-130
Number of pages24
JournalGeophysical and Astrophysical Fluid Dynamics
Issue number1-2
StatePublished - 4 Mar 2019


  • Relativistic magnetohydrodynamics (MHD)
  • chiral MHD dynamos
  • early universe
  • turbulence

ASJC Scopus subject areas

  • Computational Mechanics
  • Astronomy and Astrophysics
  • Geophysics
  • Mechanics of Materials
  • Geochemistry and Petrology


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