# Rayleigh number

(Difference between revisions)
 Revision as of 03:39, 21 September 2005 (view source)Praveen (Talk | contribs)m (Rayleigh Number moved to Rayleigh number)← Older edit Latest revision as of 03:40, 21 September 2005 (view source)Praveen (Talk | contribs) Line 6: Line 6: [/itex] [/itex] - where $g =$ acceleration due to [[gravity]] + where $g =$ acceleration due to [[gravity]], - $\alpha =$ [[coefficient of thermal expansion]] + $\alpha =$ [[coefficient of thermal expansion]], - $\Gamma =$ background [[temperature]] [[gradient]] + $\Gamma =$ background [[temperature]] [[gradient]], - $d =$ length scale of flow + $d =$ length scale of flow, - $\nu =$ [[kinematic viscosity]] + $\nu =$ [[kinematic viscosity]] and $\kappa =$ [[thermal diffusivity]] $\kappa =$ [[thermal diffusivity]]

## Latest revision as of 03:40, 21 September 2005

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