Three-fluid MHD solar wind model with eddy viscosity

Abstract

We present initial results from a three-dimensional magnetohydrodynamic (MHD) solar wind model that treats solar wind protons, electrons, and interstellar pickup protons as separate fluids and incorporates transport of turbulence and eddy viscosity. Numerical steady-state solutions of mean-field Reynolds-averaged solar wind equations coupled with turbulence transport equations are obtained by the time relaxation method in the corotating with the Sun frame of reference in the region from 0.3 to 100 AU (but still inside the termination shock). The model equations include the effects of electron heat conduction, Coulomb collisions, photoionization of interstellar hydrogen atoms and their charge exchange with the solar wind protons, turbulence energy generation by pickup protons, and turbulent heating of solar wind protons and electrons. The turbulence transport model employs the eddy viscosity approximation for the Reynolds stress tensor and turbulence phenomenologies to describe the conversion of fluctuation energy into heat via a turbulent cascade.