cicyt UNIZAR
Full-text links:

Download:

Current browse context:

physics.flu-dyn

Change to browse by:

References & Citations

Bookmark

(what is this?)
CiteULike logo BibSonomy logo Mendeley logo del.icio.us logo Digg logo Reddit logo ScienceWISE logo

Physics > Fluid Dynamics

Title: Magnetic Prandtl number dependence of turbulence generated by chiral MHD dynamos

Abstract: 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 small-scale instability. This is a microphysical effect characterised by a chiral chemical potential and is mathematically similar to the alpha effect, which is a turbulent or macrophysical effect. At high temperatures, when a chiral asymmetry can survive for long enough, these chiral MHD dynamos can amplify magnetic fields efficiently, which in turn drive turbulence via the Lorentz force. While it has been demonstrated in numerical simulations that chiral magnetically driven turbulence exists and modifies the evolution of the plasma, the details of this process remain unclear. The goal of this paper is to shed new light on the properties of chiral magnetically driven turbulence using numerical simulations with the Pencil Code. We explore the generation of turbulence for different initial conditions, including a variation of the initial chiral chemical potential and the magnetic Prandtl number, Pm. In particular, we determine the ratio of kinetic to magnetic energy, Upsilon^2, that can be reached in chiral magnetically driven turbulence. Within the parameter space explored in this study, Upsilon reaches a value of approximately 0.24-0.29 - independently of the initial chiral asymmetry and for Pm=1. Our simulations suggest, that Upsilon decreases as a power law when increasing Pm. While the exact scaling depends on the details of the fitting criteria and the Reynolds number regime, an approximate result of Upsilon(Pm)=0.3*Pm^{-0.2} is reported. Using the findings from our numerical simulations, we estimate the properties of chiral magnetically driven turbulence in the early Universe.
Comments: 18 pages, 10 figures, submitted to GAFD for the special issue "Recent Developments in Natural Dynamos"
Subjects: Fluid Dynamics (physics.flu-dyn); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); Plasma Physics (physics.plasm-ph)
Report number: NORDITA 2018-021
Cite as: arXiv:1803.06350 [physics.flu-dyn]
  (or arXiv:1803.06350v1 [physics.flu-dyn] for this version)

Submission history

From: Jennifer Schober [view email]
[v1] Fri, 16 Mar 2018 18:00:04 GMT (2947kb,D)