Vertically integrated dust density distribution after 5 Myr of evolution including radial drift and a bumpy gas surface density (Eq. (21)) with A = 0.4 (left panel) and A = 0.6 (right panel). Case of R_out = 30 AU, v_f = 10 m s^-1, p = 0.5 and α_turb = 10^-3. The solid white line represents the particle size corresponding to St = 1 (Eq. (3)) and reflects the shape of the gas density, while the cyan line corresponds to the fragmentation limit.