Exact scaling laws and the local structure of isotropic magnetohydrodynamic turbulence
This paper examines the consistency of the exact scaling laws for isotropic MHD turbulence in numerical simulations with large magnetic Prandtl numbers Pm and with Pm=1. The exact laws are used to elucidate the structure of the magnetic and velocity fields. Despite the linear scaling of certain thir...
| Main Authors: | , , |
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| 格式: | Journal article |
| 语言: | English |
| 出版: |
2006
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| 总结: | This paper examines the consistency of the exact scaling laws for isotropic MHD turbulence in numerical simulations with large magnetic Prandtl numbers Pm and with Pm=1. The exact laws are used to elucidate the structure of the magnetic and velocity fields. Despite the linear scaling of certain third-order correlation functions, the situation is not analogous to the case of Kolmogorov turbulence. The magnetic field is adequately described by a model of stripy (folded) field with direction reversals at the resistive scale. At currently available resolutions, the cascade of kinetic energy is short-circuited by the direct exchange of energy between the forcing-scale motions and the stripy magnetic fields. This nonlocal interaction is the defining feature of isotropic MHD turbulence. |
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