I am been struggling to solve the following problem:
I have a 1m plastic pipe with water flowing through (at 1m/s and 7 degrees at inlet). The pipe is submerged in soil with a constant 18 C temperature. What I am trying to find is the water temp at the pipe outlet, as a result of the soil temperature heating (something like a geothermal system). The model I have built is 3d you can see in the photo attached. There are three bodies, water at the center, surrounded by the pipe, then both surrounded by the soil.
I have created 4 interfaces, then coupled them in two walls. Now the problem is that I can't seem to find the proper boundary conditions in order to achieve water heating from soil, through the pipe and to the water.
Any help would be greatly appreciated.