A cross section through a LEGO model of a canal for water irrigation, serving as an analogy for a "Fermi pump." The left and right side of the canal are separated by a wall, at the very bottom of which is a water turbine installed in form of a worm gear. The turbine sucks in the water from deep below the water level and pumps it across. Yet, further away from the turbine the water is also drawn from higher [water] layers in the canal, as indicated by the blue arrows.
reported by Wagner and Sols in Physical Review Letters, 22 November 1999