Evolution of particle radial positions with respect to time in the case of run SI30-3-2-c. Since the particles are distributed continuously in terms of their size, we grouped them into six particle size bins. The mean position of the particles in a given size range is marked by the solid curves, while the dashed curves mark the spread of particle positions by differential radial drift and diffusion. Particles with τ_s ≥ 10⁻¹ drift and diffuse inwards, while particles of τ_s ≤ 10^−1.5 tend to move outwards in the disk. The spreading of each particle species is in fact dominated by the differential radial drift insteadof diffusion.