A Schauberger generator is a device that is purported to create a positive net gain of energy from water or air flowing through it. This functionality is disputed by many skeptics and physicists.
Viktor Schauberger was an Austrian inventor and scientist of the early 20th century. He studied the physics of natural vortexes, such as hurricanes and whirlpools. He was given several patents for his work in designing electrical generators, and also worked with the Nazi military to create a device that resembled a flying saucer.
More recently, Schauberger's ideas have been revived by several websites promoting his vortex-based technologies. Devices that are able to create energy, as the Schauberger generator is claimed to, are called "free energy" or "perpetual motion" devices, and violate the laws of thermodynamics. For this reason, most serious scientists dismiss these generators as scams. However, proponents of Schauberger insist that the way thermodynamics is currently understood is wrong, and that these devices do work.