HR: 0800h
AN: NG21B-0529    [Abstracts]
TI: Depression of Nonlinearity in the Isotropic MHD Turbulence
AU: * Servidio, S
EM: servidio@bartol.udel.edu
AF: Bartol Research Institute, University of Delaware, University of Delaware, Newark, DE 19716, United States
AU: Matthaeus, W H
EM: whm@udel.edu
AF: Bartol Research Institute, University of Delaware, University of Delaware, Newark, DE 19716, United States
AU: Dmitruk, P
EM: pablo@bartol.udel.edu
AF: Departmento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, 1428, Argentina
AB: Magnetohydrodynamic (MHD) turbulence evolves in response to a complex set of mechanical and electromagnetic stresses that drive couplings across spatial scale, leading to a cascade in which there is a net transfer of energy to small scales. Two important features of MHD turbulence, the production of spatial intermittency and the appearance of distinctive states associated with turbulent relaxation, have generally been studied independently. We show, by using decaying direct numerical simulations, that MHD turbulence generates coherent spatial correlations of several types. These are associated to the tendency of the system to develop local Beltrami fields. Moreover, a self-organization process produces anti-alignments in the magnetic and kinetic components of the acceleration. Each of these effects suppresses the nonlinearity to levels lower than the strengths obtained from "Gaussianized" fields. We conclude that this complex picture of correlations causes a local rapid cancellation of mechanical and electromagnetic forces, leading to a reduction of turbulent fluctuations. The result is the production of intermittent spatial patches.
DE: 2149 MHD waves and turbulence (2752, 6050, 7836)
DE: 2752 MHD waves and instabilities (2149, 6050, 7836)
DE: 6050 Plasma and MHD instabilities (2149, 2752, 7836)
DE: 7836 MHD waves and instabilities (2149, 2752, 6050)
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting