Rayleigh Number

Rayleigh number is used in heat transfer in general and free convection calculations in particular. It is equivalent to (Gr.Pr). It is normally defined in one of the following forms :

Rayleigh Number Calculator

Formula 1: Ra = (L³ * ρ² * g * β * ΔT * Cp) / (μ * k)

L (Characteristic length): ρ (Density): g (Gravitational acceleration): β (Coefficient of expansion): ΔT (Temperature difference): Cp (Heat capacity): μ (Viscosity): k (Thermal Conductivity):

Formula 2: Ra = (L³ * ρ * g * β * ΔT) / (μ * α)

L (Characteristic length): ρ (Density): g (Gravitational acceleration): β (Coefficient of expansion): ΔT (Temperature difference): μ (Viscosity): α (Thermal diffusivity):

alpha	=	Thermal diffusivity
beta	=	Coefficient of expansion
Cp	=	Heat capacity
delta-T	=	Temperature difference
g	=	Gravitational acceleration
k	=	Thermal Conductivity
L	=	Characteristic length
mu	=	Viscosity
rho	=	Density