A Resistive MHD Simulation of the Shear Flow Effects on the Structure of Reconnection Layer

By using a one-dimensional resistive magnetohydrodynamic (MHD) model,the Rie-mann problem is solved numerically for the structure of the reconnection layer under a shearedflow along the anti-parallel magnetic field components.The simulation is carried out for generalcases with symmetric or asymmetric plasma densities and magnetic fields on the two sides of theinitial current sheet,and cases with or without a guide magnetic field,as in various space andfusion plasmas.The generation of MHD discontinuities in the reconnection layer is discussed,including time-dependent intermediate shocks,intermediate shocks,slow shocks,slow expansionwaves,and the contact discontinuity.It is shown that the structure of the reconnection layer issignificantly affected by the presence of the shear flow.For an initial symmetric current sheet,thesymmetry condition is altered due to the shear flow.For cases with an asymmetric initial currentsheet,as at the Earth’s magnetopause,the strengths of MHD discontinuities change significantlywith the shear flow speed.Moreover,the general results for the reconnection layers in the outflowregions on either side of the X line are discussed systematically for the first time.