CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Wiki > Rayleigh number

Rayleigh number

From CFD-Wiki

Jump to: navigation, search

The Rayleigh number is the ratio of the buoyancy force to the viscous force in a medium.


Ra = \frac{g \alpha \Gamma d^4}{\nu \kappa}

where g = acceleration due to gravity, \alpha = coefficient of thermal expansion, \Gamma = background temperature gradient, d = length scale of flow, \nu = kinematic viscosity and \kappa = thermal diffusivity

My wiki