Time evolution of an unstable dust ring in a 3D simulation with parameters τ₀ = 4 × 10⁻³, Z = 0.03, and A = 0.4. The dashed and solid curves are the initial and current mid-plane gas pressure profile, respectively. One can clearly see an amplification of the gas pressure bump and unstable behavior of the dust ring, as it develops strong non-axisymmetries and splits ofa vortex which subsequently migrates inward.