Gas column density face-on (top panels of each row) and edge-on (bottom panels of each row) projections computed using the SMUGGLE model at t = 1 Gyr for all the nine simulations examined in this work, as labelled in each panel. The simulations differ in the initial value of the scale-length and of the mass of the gaseous disc (see Table 2). Each panel is 70 kpc across and in projection depth with a total number of 1024 × 1024 pixels that give a resolution of ∼70 pc. Brighter colours correspond to higher column densities, as indicated in the colorbar. In the gal_r05, gal and gal_r2 projection panels, the dashed white circle shows the disc size, R_d, defined as the radius at which the gas surface density drops below 1 M_⊙ pc⁻² (not shown in the other projections for clarity).