Evolution of similarity lengths in anisotropic magnetohydrodynamic turbulence

Abstract

In an earlier paper (Wan et al. 2012), the authors showed that a similarity solution for anisotropic incompressible 3D magnetohydrodynamic (MHD) turbulence, in the presence of a uniform mean magnetic field $\vB_0$, exists if the ratio of parallel to perpendicular (with respect to $\vB_0$) similarity length scales remains constant in time. This conjecture appears to be a rather stringent constraint on the dynamics of decay of the energy-containing eddies in MHD turbulence. However, we show here, using direct numerical simulations, that this hypothesis is indeed satisfied in incompressible MHD turbulence. After an initial transient period, the ratio of parallel to perpendicular length scales fluctuates around a steady value during the decay of the eddies. We show further that a Taylor--Kármán-like similarity decay holds for MHD turbulence in the presence of a mean magnetic field. The effect of different parameters, including Reynolds number, DC field strength, and cross-helicity, on the nature of similarity decay is discussed.

Accepted for publication in Journal of Fluid Mechanics

References in corpus (2)

• Nonuniversality and finite dissipation in decaying magnetohydrodynamic turbulence
• Energy decay laws in strongly anisotropic MHD turbulence

Cited by in corpus (6)

• Enhanced Energy Transfer Rate in Solar Wind Turbulence Observed near the Sun from Parker Solar Probe
• Pressure-Strain Interaction as the Energy Dissipation Estimate in Collisionless Plasma
• Geometry of Magnetic Fluctuations near the Sun from PSP
• Variable energy flux in turbulence
• Helios 2 observations of solar wind turbulence decay in the inner heliosphere
• Isotropization and Evolution of Energy-Containing Eddies in Solar Wind Turbulence: Parker Solar Probe, Helios 1, ACE, WIND, and Voyager 1