Cross-section of a Tesla valve, displaying its unique cavity design
A Tesla Valve, sometimes called a Tesla's Valvular Conduit, is a valve allowing for a fluid to flow very preferentially (or entirely) in one direction, but without the moving parts usually found in valves. The principle is that currents flow along different paths in different directions, and that these differences have a disproportionate effect on the resistance of the valve. Named after Nikola Tesla, it was invented in 1916 (U.S. patent 1,329,559; patented 1920). In practice, the idea has seen little development or use since its invention. A similar mechanism is used for mixing on a small scale through the use of a Coanda effect mixer.