[grassi3000]

Well, I thought about the "U" shape, because otherwise the water will take the shortest way to the outlet (in my opinion). because of the "U" it will be forced to flow through the whole wb, and not only the direct way

(like pic below, blue cold flowing water, red the water that is warmer than the rest, because it isn't in the direction of the flow)

Because of this thought, I have also implemented the obstructions.

Maybe my thoughts go into the wrong direction.

So you say, that I should only keep the U shape, and throw all the other obstructions away?

even the quad like samples, that are ony 1mm deep ( I have thought that they would make the water swirl a little bit; a friend said this would be good to)

I have also thought to replace these samples with drill holes, 1mm diameter and 1 mm deep.