Heat conduction is the transfer of heat from warm areas to cooler ones, and effectively occurs by diffusion. The heat flux is therefore
where is the density, is the mass heat capacity in erg g-1 K-1, d is the diffusion distance, and is the thermal diffusivity in cm2 s-1.
Defining the thermal conductivity (with units of erg cm-1 K-1 s-1)
and noting that is the temperature gradient, this becomes Fourier's law
Now find how temperature changes in time and space as a result of Fourier's law.
Heat Conduction Equation--1-Dimensional, Heat Conduction Equation--2-Dimensional, Heat Conduction Equation--3-Dimensional, Heat Diffusion Equation
References
McGee, H.; McInerney, J.; and Harrus, A. "The Virtual Cook: Modeling Heat Transfer in the Kitchen." Physics Today 52, 30-36, Nov. 1999.