Hi,

I need to solve the heat diffusion equation in a system with two enclosed walls.  The first wall (made of a material called fr4) goes from x=0 o x=d1, and the second wall (made of copper, that is cu)from x=d1 to x=d2. 

u(x,t) is my unknown (change of temperature with time and space) for the first wall, and v(x,t) the unknown for the second wall.

So the system of PDEs to solve is:

>PDE:=[ diff(u(x,t),t) = afr4*diff(diff(u(x,t),t) ,