Variable 𝐽. Three-dimensional simulations. Flow after the second bifurcation, for 𝐽 = 10 A m−2. (top) 𝑢𝑧at 𝑧 = −0.03 m, 𝑧 = 0 m and 𝑧 = 0.03 m. (bottom left) Contour of ||𝒖|| taken for ||𝒖|| =0.6 ||𝒖||max colored by 𝑢𝑧 . (bottom  - middle and right) ||𝒖|| at 𝑟 = 0.8𝑅 and −𝜋/2 ≤ 𝜃 ≤ 𝜋/2 (middle) and 0 ≤ 𝜃 ≤ 𝜋 (right). One sees the 𝑅𝜋 -symmetry and the periodic oscillations of the flow.