I want to simulate a heat source (eg a cpu) connected to a heatsink without any cooling fans. The simulation will run indefinitely using small time steps.
What i want to measure at each time step is the temperature of the heat source and the temperature of the heatsink at each tick (of time).
The heat source will be generating a known amount of power in watts to be converted to heat, which may vary during the simulation. Think of the cpu reducing its clockspeed thereby lowering its power consumption and heat emitted.
I believe what i need to perform each step is:
 calculate heat generated by source  emit some of that heat in the form of radiation  determine some kind of cooling  subtract cooling from heat generated to get a temperature for heatsource, and for the heatsink.
I have been messing around with heat equations but am struggling to join them together to model this system.
Any help would be very much appreciated.