Heliophysics Science Division
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A multi-equation turbulence model based on a statistical theory featuring the large-scale evolution of the solar-wind turbulence

Nobumitsu Yokoi (Institute of Industrial Science, University of Tokyo)

A model equation for the magnetohydrodynamic (MHD) residual energy (difference between the turbulent kinetic and magnetic energies) is proposed with the aid of the two-scale direct-interaction approximation (TSDIA) analysis, a statistical theory for the inhomogeneous turbulence. Combined with the equations for the turbulent MHD energy, its dissipation rate, and the cross helicity (velocity--magnetic-field correlation), a multi-equation turbulence model is developed. The model is applied to the solar wind. Some important characteristics of solar-wind turbulence obtained from spacecraft observations are discussed from the viewpoint of the inhomogeneity effects in the turbulence model. Following the application to the solar wind, some implications to time scales of turbulence are also presented.