I tried to examine the heating process of a small body on a heat sink in a transient simulation that only contained solid bodys (no fluid) and discovered a strange effect I do not understand (see attachment). I want to apply a temperature (which is changing over time) on one side of my body (which has a low thermal conductivity) and connect it to a heatsink on the other side. My simulation goal is the temperature difference across my part (over time).
I created two scenarios to simulate the same situation just in two different ways (at least I thought so) but I get different results. The only difference is that the first scenario uses a volumen heat source (set to temperature) and the second one utilizes a boundary-condition "outer-wall" (also set to temperature) both with the same temperture curve.
Does anyone know where this difference come from?
thank you in advance