Model DR_SS at t = 400, 1200 and 2000 yr (from top to bottom) and for an inclination angle i = 30°. Left: distribution of molecular gas column density. Right: mass–velocity relationship is depicted in black for each value of the j_mix parameter, from j_mix = 0.0 (first column) to j_mix = 1.0 (fourth column). The profiles were calculated considering the whole computational domain. The exponential best fit is drawn in red and the exponent v₀ is given for each j_mix value.