Gas density (top-left) and dust ratio variation maps in the xz-plane for the ten dust bins in the 256MRN run. The variations are given relative to the initial value of the quantity and are shown in logarithmic scale. In the dust-ratio panels, the red colour shows dust-ratio enhancement, while blue indicates a dust-ratio decrease. The isocontours correspond to gas-density variations of −1 (orange), 0 (black), and +1 (green) in logarithmic scale. The arrows represent the barycentric velocity (top-left), and the dust-grain drift velocity vectors in the plane for all the other plots. All plots are made at a time corresponding to 3t_cross.