IEVref: 113-04-58 ID: Language: en Status: Standard Term: Rayleigh number Synonym1: Synonym2: Synonym3: Symbol: Ra Definition: quantity of dimension 1 characterizing the relative importance of natural convection and thermal conduction, defined by $Ra=\frac{{l}^{3}{\rho }^{2}{c}_{p}\text{ }g\text{ }{\alpha }_{V}\text{ }\Delta T}{\eta \text{ }\lambda }=\frac{{l}^{3}g\text{ }{\alpha }_{V}\text{ }\Delta T}{\nu \text{ }\alpha }$, where l is a specified length, ρ is mass density, cp is specific heat capacity at constant pressure, g is acceleration of free fall, αv is the cubic expansion coefficient, T is thermodynamic temperature, η is dynamic viscosity, λ is thermal conductivity, and α is thermal diffusivityNOTE The Rayleigh number is the product of the Grashof number Gr and the Prandtl number Pr, thus Ra = Gr ⋅ Pr. Publication date: 2011-04 Source: Replaces: Internal notes: 2015-11-02: Note corrected from "NOTE The Rayleigh number is the product of the Grashof number Re" to "NOTE The Rayleigh number is the product of the Grashof number Gr" in accordance with mail from Reinhard Salffner. JGO 2017-06-02: Cleanup - Remove Attached Image 113-04-58en.gif CO remarks: TC/SC remarks: VT remarks: Domain1: Domain2: Domain3: Domain4: Domain5: