Alignment of the scalar gradient in evolving magnetic fields

Abstract

We conduct simulations of turbulent mixing in the presence of a magnetic field, grown by the small-scale dynamo. We show that the scalar gradient field, $\nabla C$, which must be large for diffusion to operate, is strongly biased perpendicular to the magnetic field, $\mathbf{B}$. This is true both early-on, when the magnetic field is negligible, and at late times, when the field is strong enough to back react on the flow. This occurs because $\nabla C$ increases within the plane of a compressive motion, but $\mathbf{B}$ increases perpendicular to it. At late times the magnetic field resists compression, making it harder for scalar gradients to grow and likely slowing mixing.

ApJ Letters (in press)

References in corpus (14)

• Simulations of small-scale turbulent dynamo
• Metallicity of the intergalactic medium using pixel statistics. II. The distribution of metals as traced by C IV
• Growth of Magnetic Fields Induced by Turbulent Motions
• High Redshift Metals I.: The Decline of C IV at z > 5.3
• The Sources of Intergalactic Metals
• Fluctuation dynamos and their Faraday rotation signatures
• Characteristic Lengths of Magnetic Field in Magnetohydrodynamic Turbulence
• Mixing in Supersonic Turbulence
• The Spatial Distribution of Metals in the Intergalactic Medium
• The Clustering of Intergalactic Metals
• Modeling the Pollution of Pristine Gas in the Early Universe
• Mixing of Primordial Gas in Lyman Break Galaxies
• Mixing in Magnetized Turbulent Media
• Suppression of local heat flux in a turbulent magnetized intracluster medium

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• Inaccuracy of Spatial Derivatives in Simulations of Supersonic Turbulence