Initial configuration, consisting of a plane current sheet with different magnetic field strengths and densities on the two sides. Solid black lines are magnetic field lines with the higher field strength on side 2. Color indicates plasma density. The shaded oval in the center indicates a resistive “spot,” located at and , which may move in time. For one set of simulations a finite inflow was employed at , leading to a deformation of the external fields indicated by the red lines; for details, see text.
Evolution of a nondriven run (case C), showing magnetic field lines (solid black lines) and the velocity component (color scale) for a resistive MHD simulation with a localized resistivity given by Eq. (16) with , , .
Evolution of the reconnected flux (top) and the reconnection rate (bottom) for a nondriven run (case C) with a localized resistivity given by Eq. (16) with , , . The reconnection rate in the bottom panel is evaluated in two ways, by the value of at the reconnection site (solid line) and by the temporal change of the reconnected flux (dashed line).
Evolution of the reconnected flux (top) and the reconnection rate (bottom) for a driven run with a localized resistivity given by Eq. (16) with , , , for three different box lengths . The inflow was the same in all cases, confined to .
Comparison of the flow characteristics for nondriven runs A–D at the times of maximum reconnection rate, using localized resistivity given by Eq. (16) with . Only a central part of the simulation box is shown, with magnetic field lines (solid black lines) and the velocity component (color scale). Thin white contours show contours of , indicating the diffusion region. Heavy blue and white lines indicate plasma paths that lead from a location at (small circles) into the region of fast outflow.
Same as in Fig. 5 but showing the density (color). Plasma trajectories into the region of fast outflow are again shown as heavy colored lines.
Maximum reconnection rates as a function of resistivity for (left) driven and (right) nondriven cases A–D and different normalizations indicated in the figure. The top panels correspond to our initial scaling. The center panels are based on Eq. (24), representing the Cassak–Shay formula (8) applied to the high-resistivity regime, and the reconnection rates in the bottom panels are scaled with Eq. (25), using the same formula but with an Alfvén speed based on the actual density at the reconnection site.
Electric field contributions as functions of in the vicinity of the reconnection site for nondriven cases A–D, defined in Table I, with , evaluated in a frame moving with a speed defined by Eq. (27).
Initial parameters for four characteristic cases.
Energy flow into and out of the reconnection site for nondriven runs A–D with , evaluated at the times of maximum reconnection rate.
Energy transfer terms for nondriven runs A–D with , evaluated at the times of maximum reconnection rate; represents the total transfer to enthalpy flux, column 2 plus column 4, and the transfer to kinetic energy flux, column 3 minus column 4.
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