Residual energy in magnetohydrodynamic turbulence and in the solar wind
arXiv:1108.6072 · doi:10.1063/1.4723584
Abstract
Recent observations indicate that kinetic and magnetic energies are not in equipartition in the solar wind turbulence. Rather, magnetic fluctuations are more energetic and have somewhat steeper energy spectrum compared to the velocity fluctuations. This leads to the presence of the so-called residual energy E_r=E_v-E_b in the inertial interval of turbulence. This puzzling effect is addressed in the present paper in the framework of weak turbulence theory. Using a simple model of weakly colliding Alfvén waves, we demonstrate that the kinetic-magnetic equipartition indeed gets broken as a result of nonlinear interaction of Alfvén waves. We establish that magnetic energy is indeed generated more efficiently as a result of these interactions, which proposes an explanation for the solar wind observations.
To appear in "Physics of the Heliosphere: a 10-year Retrospective", Jacob Heerikhuisen, Gang Li, and Gary P. Zank, Eds
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- Pressure-anisotropy-induced nonlinearities in the kinetic magnetorotational instability
- Influence of the heliospheric current sheet on the evolution of solar wind turbulence
- Reynolds number dependence of Lagrangian dispersion in direct numerical simulations of anisotropic magnetohydrodynamic turbulence
- Evolution of MHD turbulence in the expanding solar wind: residual energy and intermittency