Rayleigh-Bénard Convection

Thermal instability forming organized roll patterns

40×10³
300
2×
When a fluid layer is heated from below, the Rayleigh-Bénard instability occurs above a critical Rayleigh number Rac ≈ 1708. Hot fluid rises, cool fluid sinks, forming organized convection rolls. The roll width-to-height ratio is approximately √2. At higher Ra, rolls give way to chaos and eventually turbulence.