Random selection of dust trajectories in TD20, for three a₀; the image has been zoomed in to the inner 110 AU × 110 AU to give a better view of the region around the outer gap. The grains are launched from the disk surface (orange dashed line) and if picked up by the wind, they then follow the gas streamlines (grey dotted lines) more or less closely, depending on their local Stokes number St (colourbar). A few of the grains are not entrained, and proceed to move into the disk, following the gas flows there.