Thanks Chestermiller for reply, "What is the relevance of the beam being cantilevered?" good point there no practical relevance the only thing is V is connected to the fixed end and V0 is connected to the free end. "What is the thermal boundary condition at the cantilever end of the beam." Actually there is another cantilever on the other end , both are connected at the center so we can assume free end surface is loosing heat (equivalent to the actual conduction into the other cantilever) "Do you need to include the heat transfer from the beam to the air" No we can neglect the convection lose.
Thanks.