Formation of the CME sheath in the different simulation runs. Shown are the evolution of the radial extent of the sheath (a), the flux rope leading edge (b), and the location of the CME shock along a viewing angle of 105° (c) for the simulation runs detailed in Table 1. The individual runs at time t = 21 min are visualised in (d)–(i); the magnetic field lines are colour-coded according to the case number. In each panel d–i, the viewing angle, the flux rope, and shock locations are also indicated.