# little pdepe problem with heat-transfer

Hello everyone

I am facing a little problem by programming matlab to compute a heat-transfer situation:
We have a holed-cylinder with the inner radius 0.295m and the outer radius 0.655m. In between we have 4 different sheets each one consisting of a different material, this means every sheet has its own Thermal conductivity and density (Heat capacity is the same everywhere).
Now, in the inner side of the cylinder the temperature is been held constant at 600 degrees Celcius. At the outer side of the cylinder heat is give to the environment via convection (Heat transfer coefficient of a=20 W/(m^2K). The environment temperature is 20 degrees Celcius. All the coefficients of all the different materials are known. I want to see what happens in case the cylinder has everywhere the temperature 600 and is been let for a long time until we reach a steady-state temperature as function of the radius. Ofcourse I can calculate this analytic (I already did), but I want to see what happens in between throughout the time point zero and infinitely. So I have to "surf" it.

I created this code with Matlab. It looks korrekt, but the end-temperatures don