Evolution of the midplane density of gas and 2 cm dust (). The times are given in Keplerian time T_B at r = r_B = 3 AU after the addition of the dust grains, where r_B is the position of the initial density bump. At t = 0 the dust population is axisymmetric. The densities are normalised to ρ₀, and the colour bar used for the dust density follows the increase in this quantity, whereas the gas density colour bar is fixed.