Time evolution of the barycentre and dust-species RMS velocity (top) and of the clumping factor of the density of the different species (bottom) in the fiducial model 256MRN. The time evolution has been normalised according to the turbulent crossing time t_cross. In the bottom panel, the dotted line shows the clumping factor evolution of the total dust density ρ_d and the dashed-dotted line shows the clumping factor evolution of each dust species concentration ϵ_i. The evolution of the clumping factor of the gas density (dashed) is indistinguishable from that of the barycentre (solid) density.