Channel maps of H I gas distribution of NGC 5238 computed from the reference simulations of Sect. 4. The channels width is 3 km s⁻¹, with the average channel velocity reported in each panel. The red curves show H I column densities of 0.5, 2 and 8 M_⊙ pc⁻² while, in black, the same 0.5, 2 and 8 M_⊙ pc⁻² isodensities but computed from the total gas distribution. The bottom panels show the overall gas-mass weighted line-of-sight velocity field in the simulation (left) and in the VLA observation (Cannon et al. 2016): blue colors and negative velocities correspond to the disc approaching arm, while red colors and positive velocities to the disc receding arm. The velocity field in the simulation extends down to column densities of 0.5 M_⊙ pc⁻². The panel size is 5.5 kpc × 5.5 kpc.