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arXiv · 0712.2024

Energy decay laws in strongly anisotropic MHD turbulence

Barbara Bigot·Sebastien Galtier·Helene Politano
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Abstract

We investigate the influence of a uniform magnetic field ${\bf B_0}=B_0 e//$ on energy decay laws in incompressible magnetohydrodynamic (MHD) turbulence. The nonlinear transfer reduction along $B_0$ is included in a model that distinguishes parallel and perpendicular directions, following a phenomenology {\it à la} Kraichnan. We predict a slowing down of the energy decay due to anisotropy in the limit of strong $B_0$, with distinct power laws for energy decay of shear- and pseudo-Alfvén waves. Numerical results from the kinetic equations of Alfvén wave turbulence recover these predictions, and MHD numerical results clearly tend to follow them in the lowest perpendicular planes.

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Barbara Bigot, Sebastien Galtier, Helene Politano. 2007-12-12. Energy decay laws in strongly anisotropic MHD turbulence. https://doi.org/10.1103/physrevlett.100.074502

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