Left: contours of the midplane density obtained in Model 1 with the NIRVANA run, and time-averaged between 520 and 555 orbits. Streamlines in the disc midplane, time-averaged over the same time interval, are overplotted by solid curves. Right: gas surface density obtained at 520 orbits with disc Model 1 in the FARGO viscous run, with instantaneous streamlines overplotted. In both panels, the horizontal dashed line shows the planet’s corotation radius, defined as the location R_c where Ω(R_c) = Ω_p.