# Rayleigh Number

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Ra =
Tags:
Rating
ID
MichaelBartmess.Rayleigh Number
UUID
56c84284-151c-11e3-8615-bc764e049c3d

The Rayleigh Number (Ra) is a measure of the strength of the conduction or convection as a mechanism for the transfer of energy.  This equation is the same as the equation in Physics / Thermodynamics.

Conduction is the transfer of energy between objects that are in physical contact and convection is the transfer of energy between an object and its environment due to motion of fluids or gases.

The inputs to this equation are:

• g = gravitational acceleration
• rho = the density difference
• mu = dynamic viscosity
• L = length
• alpha = thermal diffusivity

The output Rayleigh number is a dimensionless number