SELF-CONSISTENT AND TIME-DEPENDENT SOLAR-WIND MODELS

We describe the first results from a self-consistent study of Alfven w aves for the time-dependent, single-fluid magnetohydrodynamic (MHD) so lar wind equations, using a modified version of the ZEUS MHD code. The wind models we examine are radially symmetrical and magnetized; the i nitial outflow is described by the standard Parker wind solution. Our study focuses on the effects of Alfven waves on the outflow and is bas ed on solving the full set of the ideal nonlinear MHD equations. In co ntrast to previous studies, no assumptions regarding wave linearity, w ave damping, and wave-flow interaction are made; thus, the models natu rally account for the back-reaction of the wind on the waves, as well as for the nonlinear interaction between different types of MHD waves. Our results clearly demonstrate when momentum deposition by Alfven wa ves in the solar wind can be sufficient to explain the origin of fast streams in solar coronal holes; we discuss the range of wave amplitude s required to obtained such fast stream solutions.