how to deal with the 3rd heat transport boundray

HI all,

I want to simulate a shallow aquifer heat pumpimg system, and i define a 3rd heat BC for the upper surface boundary condition of the heat transport problem.

so the question is should I set the 3rd heat BC on all  nodes or only nodes on the four sides  in the first slice ?

Kind regards

If the 3rd kind bc represents the heat transfer between underground and air, the boundary condition should be set all over the model in the first slice.

oh, i see. thank you very much.

but i can not understand the meaning of "transfer rate in or out"
does it equivalent to the ratio of conductivity of unsaturated zone and the thickness of unsaturated zone?
and the value of the transfer rate in and out-fluxs maybe the same?

I am sorry to disturb you many times, your answer is very helpful to me, thank you again

in my model, initial temperature of groundwater is 15 ??and the temperature of injection water is 10??but how to explian the temperature of some nodes exceed 15 ? almost on every slice.

Values higher than 15 degrees indicate an instable model with oscillations. Please refer to the literature about oscillations in numerical models and how to deal with them. The most imporant is a relatively fine calculation mesh.