Temporal evolution of the vorticity squared (top panel) and the current density squared (bottom panel) integrated in the whole computational domain. The vorticity values are normalized with respect to the initial value. The two dashed black lines show respectively the onset of the Kelvin–Helmholtz instability inferred from the analysis of azimuthal modes, τ_KH = 70, and the time at which the integrated vorticity squared saturates, τ_sat = 300.