A true 3D fluid: a velocity+smoke grid that's advected, made incompressible (pressure solve), and given curl (vorticity confinement). Drag in the view to grab the ball and stir; release to watch it billow. The smoke is carried by the flow, so it tears and swirls like the real thing, not pushed paint.
vorticity = how much it curls/billows. power = jet strength. ventilation = a room draft that slowly clears the smoke.