Side and top views of the particle layer for a 3D model with particles of τ_s = 10^-2 and a solid abundance of Z = 0.02. The time t in terms of the local orbital period P increases from left to right. The top panels show the azimuthal average of the particle density ρ_p with respect to the initial gas density in the mid-plane ρ₀, while the bottom panels show the column density of solids Σ_p with respect to the initial column density of gas Σ₀. The coordinates are normalized by the vertical scale height of the gas H. The model has a computational domain of 0.2H on each side and a resolution of 640H^-1.