Snow Globe Fluid Dynamics (3D)

This 3D snow globe is a real viscous-fluid simulation, not a scripted snow-swirl animation. Shaking it (or dragging across it) injects genuine Lamb-Oseen vortices into the fluid, whose swirl speed decays exactly as viscous diffusion predicts — the vortex core radius grows as a(t)² = a₀² + 4νt. Every glitter particle is simultaneously advected sideways by that decaying velocity field and pulled down by its own Stokes-drag terminal velocity, v_t = 2r²(ρ_p−ρ_f)g/(9η), so bigger or denser particles in thinner fluid sink measurably faster while the swirl still carries lighter ones sideways. Adjust viscosity, particle size, particle density and fluid density to watch the settling time and swirl pattern change in real time, and shake again to re-suspend anything that has already settled.