Hello, I am facing one problem in heat transfer. In one of my projects, I have to calculate heat transfer capacity (or Thermal Resistance) of a particular heat sink. I have to check whether that heat sink will be efficient to dissipate heat generated by device mounted on it or not. Heat sink is Finned Heat Sink. I know how to calculate thermal resistance of heat sink where fins are at the one side of base only, & where heat generating device is mounted on base. i.e Rfins But this particular heat sink has "T" shaped structure. Here, device is mounted on head of "T" i.e. short side of T & fins ara at both side of leg of "T" i.e. Long side of T. Now, about the difficulty I am facing:- 1) I have calculated thermal resistance of one side of finned heat sink considering device is mounted at the base of heat sink. for this heat sink , how do I need to consider two resistances (for two finned side) in parallel connection or in series? 2) Also, how the thermal resistance of surface, where device is mounted, i.e. Rhead will be connected to thermal resistance of fins? i.e. in parallel connection or series connection? 3) Also, do I have to multiply thermal resistance of base of fins i.e. Rbase by 2? kindly help me in this issue.