Energy decay laws in strongly anisotropic magnetohydrodynamic turbulence.
We investigate the influence of a uniform magnetic field B(0)=B(0)e( parallel) 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 of 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.
Bigot
Barbara
B
Institut d'Astrophysique Spatiale, Bâtiment 121, F-91405 Orsay (France); Université Paris-Sud XI and CNRS (UMR 8617), France.
Galtier
Sébastien
S
Politano
Hélène
H