Two-dimensional, time-dependent mhd simulation of the disturbed solar wind due to representative flare-generated and coronal hole-generated disturbances

Abstract

A two-dimensional, time-dependent, magnetohydrodynamic (MHD), numerical model is used to simulate several types of high speed stream interactions with an ambient, undisturbed solar wind flow.The physical origins of these two types of interactions are achieved by assuming that the high speed streams are generated by the occurrence of two "forcing" phenomena: (i) a temporally-limited energy release represented by a transient flare; and (ii) a newly-created, coronal hole-generated high speed stream which continues, unabated, to add energy into the original, background solar wind flow. Because of the difference in the time scales of a flare and an evolving coronal hole, the development of the disturbed flow behind flare-generated and coronalhole-generated shocks is different. That is, the latter can be initiated on a time scale of a day but can continue for one or more solar rotations. The former can be initiated on only a time scale of minutes or an hour after which its decay is measured within another hour or two.Therefore, we have initiated a study of these two cases by simply varying the time duration of the disturbances in the initial-value calculation. Thus, several differences in dynamical behavior for the solar wind interaction with a coronal-hole-generated shock and that due to a flare-generated shock are exhibited in this study, In the former case, a unique result was the development of an outward-travelling magnetic "bubble".