A Numerical Study on the Interaction Between 2 Ejecta in the Interplanetary Medium: 1 and 2 Dimensional Hidrodynamic Simulations

We studied the heliospheric evolution in 1 and 2 dimensions of the interaction between two ejecta-like disturbances. The study is based on a hydrodynamic single fluid model using the ZEUS-3D code. These simple numerical simulations illuminate several aspects of the heliocentric evolution of the ejecta and their associated IP shocks. The simulation shows that when a fast ejecta 2 overtakes a previously launched slower ejecta 1 in the solar wind, occurs an interchange of momentum between the two ejecta, the leading slower ejecta 1 accelerates and the tracking faster ejecta 2 decelerates. Both ejecta tend to arrive to 1 AU having similar speeds. Associated with this transfer of momentum between the two ejecta, the forward shock leading the disturbances accelerates becoming stronger.