I agree, the U test is very hard. I spent many days trying to make a working 2D approximation with cellular automata, but I couldn't find any way to make the pr

I agree, the U test is very hard. I spent many days trying to make a working 2D approximation with cellular automata, but I couldn't find any way to make the pressure propagation fast enough. The water would eventually level out on both sides of the U, but it took a very long time to do it.