Evolution of Kelvin-Helmholtz instability at Venus in the presence of the parallel magnetic field

Two-dimensional MHD simulation was performed to study the evolution of Kelvin-Helmholtz (KH) instability on Venusian ionopause in response to the strong sheared velocity flow in presence of the in-plane magnetic field parallel to the direction of the flow. The Key result from our simulations is that both of the density increase and the parallel magnetic component on the boundary layer play a role of stabilizing the instability. In the high density ratio cases, the value of final total magnetic energy in the quasi-steady status is much more than that of the initial status, which is quite distinct from that with low density increase. The nonlinear development of case with high density increase and uniform magnetic field is of interest that a single magnetic island forms before the instability saturation. In the non-linear development phase, a new magnetic island arises associated with magnetic reconnection occurring inside the narrow high rolled up density region, combining the pre-existing magnetic island together to form a quasi-steady two island pattern.