Comparison between the jet structure predicted by our model and the results of numerical simulations by Lazzati et al. (2017b). Upper panel: distribution of kinetic energy per unit solid angle, while Lower panel: average Lorentz factor diminished by one. Grey dashed and dotted lines represent respectively the jet and the cocoon as computed by our model (Sects. 3, 4 and 4.2). Red lines show the combined structure. Blue thick lines show the results of the numerical simulations (the Lorentz factor profile is given in Lazzati et al. 2018).