In physics and engineering, the Fourier number (Fo) or Fourier modulus, named after Joseph Fourier, is a dimensionless number that characterizes heat conduction. Conceptually, it is the ratio of the heat conduction rate to the rate of thermal energy storage. It is a dimensionless time, which with the Biot number, characterizes transient conduction problems. It is defined as:
- <math>\mbox{Fo} = \frac{\alpha t}{R^2}</math>
where:
- α is the thermal diffusivity [m2/s]
- t is the characteristic time [s]
- R is the length through which conduction occurs [m]
References
- Fundamentals of Heat and Mass Transfer, Incropera & DeWitt
