Theory and simulations of the scaling of magnetic reconnection with symmetric shear flow

Abstract

The scaling of magnetic reconnection in the presence of an oppositely directed sub-Alfvénic shear flow parallel to the reconnecting magnetic field is studied using analytical scaling arguments and two-dimensional two-fluid numerical simulations of collisionless (Hall) reconnection. Previous studies noted that the reconnection rate falls and the current sheet tilts with increasing flow speed, but no quantitative theory was presented. This study presents a physical model of the effect of shear flow on reconnection, resulting in expressions for the scaling of properties such as the reconnection rate, outflow speed, and thickness and length of the dissipation region, which are verified numerically. Differences between Hall and Sweet-Parker reconnection are pointed out. The tilting of the current sheet is explained physically and a quantitative prediction is presented and verified.