Nonsteady-state heat conduction in a cylinder obeys the following PDE:

,
where

is the thermal diffusivity coefficient expressed in

,

is the temperature in

, and

is the radial position in meters.
The initial condition and boundary conditions are

(initial temperature);

(the temperature at the cylinder surface is kept constant);

(symmetry condition).
This Demonstration shows the temperature profile inside the cylinder at different instants for values of the thermal diffusivity coefficient specified by the user.