M_d(t), mass of the torus, normalised with respect to the starting mass at the initial moment of the simulation, M_d(0), is plotted as a function of time for different values of q = 0.6 (dotted), 0.8 (dot-dashed), 1.0 (dashed), 1.1 (solid). Top panel: a = 0.3; bottom panel: a = 0.9. For small q and small a the torus is unstable and its mass becomes quickly accreted onto the black hole, whereas higher values of the slope of the angular moment distribution and fast spin of the black hole tend to stabilise the system against the initial perturbation (accretion stops at a certain moment).