FIRST RESULTS ON MHD SIMULATION OF MAGNETIC CLOUDS USING A ROE-TYPE APPROXIMATE RIEMANN SOLVER

Abstract. The magnetoplasma associated with magnetic clouds inside the solar wind is analyzed. Especially, the behaviour of magnetoplasma in the sheath region between the cloud and its shock front will be simulated using a Godunov scheme for solving the system of governing equations for ideal magnetohydrodynamics. A Roe-type Riemann solver is applied on a two-dimensional semi-geodetic grid reflecting the idealized cylindrical structure of magnetic clouds. Two case studies are presented to test the validity of the numerical algorithm. First, the magnetic cloud is modelled as a solid obstacle and the flow of the solar wind plasma around this obstacle is simulated. Second, the boundary of the magnetic cloud is provided with a magnetic field causing magnetic reconnection to appear on the front side of the magnetic cloud and leading to an expansion of the cloud’s diameter. 1