Fourier number

Summary

The Fourier number $\mathrm{Fo} = \alpha t / L^2$ is the dimensionless time of heat conduction. Here $\alpha$ is the thermal diffusivity, $t$ is time, and $L$ is a length of the body. It compares the time elapsed with the time heat needs to diffuse across the body. For bodies of the same shape with the same dimensionless initial and boundary data, solutions of the heat equation depend on time only through $\mathrm{Fo}$.