Azimuth-averaged radial profiles of the particle/gas properties in the mid-plane at t = 600P for the 3D model with particles of τ_s = 10^-2 and a resolution of 640H^-1. The top, middle, and bottom panels show densities, radial velocities, and azimuthal velocities with respect to the background Keplerian shear, respectively. The blue (left axis) and the green (right axis) lines represent the gas and the solid particles, respectively. The background density gradient is added to the gas profile for easy recognition of any pressure bump (see Appendix B). The gas and the particle densities are normalized by the initial gas density in the mid-plane ρ₀, while the velocities are weighted by the densities and normalized by the velocity reduction of the gas Δv = Πc_s due to external radial pressure gradient (Sect. 2). We note that a zero velocity is equivalent to moving at the Keplerian velocity, irrespective of the location.