Fourier Number

Fourier number, abbreviated as Fo, also called Fourier modulus, a dimensionless number, 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.

 

Fourier number formula
\(\large{ Fo = \frac{\alpha \; t_c }{l_c^2  }  }\)
Symbol	English	Metric
\(\large{ Fo }\) = Fourier number	\(\large{ dimensionless }\)
\(\large{ l_c }\) = characteristic length	\(\large{ ft }\)	\(\large{ m }\)
\(\large{ t_c }\) = characteristic time	\(\large{ sec }\)	\(\large{ s }\)
\(\large{ \alpha }\)  (Greel symbol alpha) = thermal diffusivity	\(\large{\frac{ft^2}{sec}}\)	\(\large{\frac{m^2}{s}}\)

 

Fourier number calculator