# Thermal resistance of a rod

I have a confusion about how to calculate the thermal resistance of a solid rod ( not hollow).

The general formula is $$R=\ln(r2/r1)/(2\pi Lk)$$ In my case, $$r1=0$$

Any hint would be highly appreciated.

• yes correct, normally in my case, exercices are solved by using temperature distribution equation, but I just wanted to see how to calculate thermal resistance in my case, I thought that maybe I could put r1=0.01 but still someone has a better idea? Commented Jan 7, 2019 at 9:18
• I need to confirm that there is no direct formula , maybe the only solution is to Q˙=ΔT/R so we need to find heat transfer rate and the ΔT before calculating?? Commented Jan 7, 2019 at 9:24
• Use the analogy of ohm's law and heat current Commented Jan 7, 2019 at 10:00
• yes, I guess this is what I mentioned, thanks for confirming! Commented Jan 7, 2019 at 10:01
• Sorry, on reflection I have realised that the formula that you have quoted predicts the heat flow through the walls of a pipe not along the length of a pipe. Commented Jan 7, 2019 at 10:06