Diffusive Instabilities in Dusty Disks: Linear Growth and Nonlinear Breakdown
The study investigates diffusive instabilities in dusty disks by including a viscous gas that couples to dust via drag. Linear analysis shows instability occurs when the dust diffusion slope ($eta_{diff}$) is less than approximately -2. Nonlinear simulations reveal that under simple power-law closures, the instability drives finite-time collapse into sharp spikes rather than saturating, suggesting more complex physics is needed for realistic saturation.