Logarithm of the average shell radius vs. logarithm of time for the different models. Time is plotted relative to the first available snapshot for each run at about 0.2 Myr. The dashed lines are linear fits with the slope mentioned on the bottom right of the plot. The analytical radius-time relation, R(t) ∝ t^3/5, almost coincides with the black dashed line; the offset with respect to the dashed lines was introduced for illustration purposes.