Heavy fluid atop light fluid — mushroom fingers from small perturbations
When a dense fluid (blue) overlies a less dense fluid (orange), the interface is gravitationally unstable. Small perturbations grow exponentially at rate σ = √(Ag·k) where A=(ρ₁−ρ₂)/(ρ₁+ρ₂) is the Atwood number and k is wavenumber. Click the canvas to add local perturbations. This mechanism drives supernova explosions and inertial confinement fusion implosions.