Components of the velocity perturbation in a horizontal cut at 2 Mm for θ = 15° at a time of 112 s after the start of the simulation. The velocities are given in m s⁻¹ and the spatial scales are in Mm. The black pseudo-circles show the β = 1 contour, with β ≫ 1 inside and β <  1 outside the loops. The values of the first two pixels next to the margin are set to zero for the normal and azimuthal component, as the corresponding vectors were badly defined in that region. The temporal evolution is available as an online movie.