Goddard Space Flight Center
MHD Simulations of the Solar Wind
We describe a three-dimensional simulations model of the heliosphere from a source surface near the base of the corona out to about 100 AU. With this model, we are able to simulate the global steady-state structure of the solar corona and solar wind. The large-scale solar magnetic field is assumed to be a dipole, although the model has also been used with quadrupole and octopole contributions. The axis of the dipole is inclined by 30 degrees to the solar rotation axis, which models solar conditions typical for the declining phase of the solar activity cycle. At large heliospheric distances, the model includes the effects of interstellar neutral hydrogen that is ionized as it enters the heliosphere. The interaction of those "pickup protons" with the ambient solar wind affects the velocity, temperature, and density of the wind. The simulations can also model the formation of corotating interaction regions and the heliospheric current sheet. The simulations are also capable of describing very strong rarefaction regions that include embedded sub-Alfvénic regions that form on the trailing edge of a fast flows.