Acceleration of plasma flows in the closed magnetic fields: Simulation and analysis

Within the framework of a two-fluid description, possible pathways for the generation of fast flows (dynamical as well as steady) in the closed magnetic fields are established. It is shown that a primary plasma flow (locally sub-Alfvénic) is accelerated while interacting with ambient arcade-like closed field structures. The time scale for creating reasonably fast flows (>~100 km/s) is dictated by the initial ion skin depth, while the amplification of the flow depends on local plasma β. It is shown that distances over which the flows become ``fast'' are ~0.01R₀ from the interaction surface (R₀ being a characteristic length of the system); later, the fast flow localizes (with dimensions <~0.05R₀) in the upper central region of the original arcade. For fixed initial temperature, the final speed (>~500 km/s) of the accelerated flow and the modification of the field structure are independent of the time duration (lifetime) of the initial flow. In the presence of dissipation, these flows are likely to play a fundamental role in the heating of the finely structured stellar atmospheres; their relevance to the solar wind is also obvious.