Evolution of the particle density distribution for 2D models with particles of dimensionless stopping time τ_s = 10^-2. The top, middle, and bottom panels show the models with an increasing solid abundance of Z = 0.01, 0.02, and 0.04, respectively, and the time t in terms of the local orbital period P increases from left to right. The particle density ρ_p is measured with respect to the initial gas density in the mid-plane ρ₀, and the radial and vertical positions are expressed in terms of the vertical scale height of the gas H. The models have a computational domain of 0.2H × 0.2H and a resolution of 2560H^-1.