Rayleigh-Bénard Convection Rolls

Parameters

Ra_c = 1708:
Nu (Nusselt):
Re (Reynolds):
Rayleigh-Bénard: heated from below, cooled from above. Convection onset at Ra = 1708 (Rayleigh 1916).

Ra = gαΔTd³/(νκ) — buoyancy vs diffusion. Pr = ν/κ — momentum vs thermal diffusivity.

Above Ra_c, rolls form; at higher Ra → oscillations → chaos → turbulence.