Fourier Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Fourier number, abbreviated as Fo, is a dimensionless number that is the ratio of heat conduction rate to the rate of thermal energy storage in a solid.  This is mainly used in unsteady state heat transfer. The Fourier Number Formula & Calculation is below.

 

\(\large{ Fo = \frac{\alpha t}{l^2  }  }\)         

Where:

\(\large{ Fo }\) = Fourier number

\(\large{ l_c }\) = characteristic length

\(\large{ \alpha }\)  (Greel symbol alpha) = thermal diffusivity

\(\large{ t }\) = time

 

Solve for:

\(\large{ \alpha = \frac{  Fo l^2    }{ t }   }\)

\(\large{ t = \frac{  Fo l_{c}{^2}  }{ \alpha }   }\)

\(\large{ l_c =  \sqrt   { \frac{ \alpha t }{ Fo }  }   }\)

 

Tags: Equations for Heat Transfer Equations for Temperature