The scaling properties of two-dimensional compressible magnetohydrodynamic turbulence

The scaling properties of two-dimensional compressible magnetohydrodynamic turbulence

The scaling properties of two-dimensional compressible magnetohydrodynamic turbulence 150 150 UKAEA Opendata

The scaling properties of two-dimensional compressible magnetohydrodynamic turbulence

Understanding the phenomenology captured in direct numerical simulation (DNS) of magnetohydrodynamic (MHD) turbulence rests upon models and assumptions concerning the scaling of field variables and dissipation. Here compressible MHD turbulence is simulated in two spatial dimensions by solving the isothermal equations of resistive MHD on a periodic square grid. In these simulations it is found that the energy spectrum decreases more slowly with k , and the viscous cutoff length is larger, than would be expected from the 1941 phenomenology of Kolmogorov (K41). Both these effects suggest that the cascade time is modified by the presence of Alfvén waves as in the phenomenology of Iroshnikov and Kraichnan (IK). Motivated by this, these scaling exponents are compared with those of the IK-based model of Politano and Pouquet [Phys. Rev. E 52 , 636 (1995)], which is an extension of the model of She and Leveque [Phys. Rev. Lett. 72 , 336 (1994)]. However, the scaling exponents from these simulations are not consistent with the model of Politano and Pouquet, so that neither IK nor K41 models would appear to describe the simulations. The spatial intermittency of turbulent activity in such simulations is central to the observed phenomenology and relates to the geometry of structures that dissipate most intensely via the scaling of the local rate of dissipation.

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12/01/2006