Energy Decay Laws in Strongly Anisotropic Magnetohydrodynamic Turbulence
Résumé
We investigate the influence of a uniform magnetic field B0 B0ek on energy decay laws in incompressible magnetohydrodynamic (MHD) turbulence. The nonlinear transfer reduction along B0 is included in a model that distinguishes parallel and perpendicular directions, following a phenomenology of Kraichnan. We predict a slowing down of the energy decay due to anisotropy in the limit of strong B0, with distinct power laws for energy decay of shear- and pseudo-Alfve'n waves. Numerical results from the kinetic equations of Alfve'n wave turbulence recover these predictions, and MHD numerical results clearly tend to follow them in the lowest perpendicular planes.
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