Fourier number

The Fourier number is frequently used as a nondimensional time parameter.

Convert time to the Fourier number.

A nomogram has relative temperature as the y coordinate and the Fourier number, which is calculated by:

The Biot number increases as the Fourier number decreases.

Together with the Biot number, the Fourier number can be used to solve unsteady state conduction problems.

Since materials differ in their Biot numbers, the time it takes for the material to quench, or the Fourier number, will vary in practice.

If the Biot number is less than 0.1, the following equation derived from the Biot and Fourier numbers can be used to find the time.

For transient mass transfer by diffusion, there is an analogous mass Fourier Number (also denoted Fo) defined as:

In physics and engineering, the Fourier number (Fo) or Fourier modulus, named after Joseph Fourier, is a dimensionless number that characterizes heat conduction.

In steel, the quenching temperature range is generally from 600 C to 200 C. To control the quenching time and to select suitable quenching media, it is necessary to determine the Fourier number from the desired quenching time, the relative temperature drop, and the relevant Biot number.