A jet is an efflux of fluid that is projected into a surrounding medium, usually from some kind of a nozzle, aperture or orifice. Jets can travel long distances without dissipating. In the Earth's atmosphere there exist jet streams that travel thousands of miles.
Jet fluid has higher momentum compared to the surrounding fluid medium. In the case where the surrounding medium is assumed to be made up of the same fluid as the jet, and this fluid has a viscosity, then the surrounding fluid near the jet is assumed to be carried along with the jet by a process called Entrainment (hydrodynamics).
Some animals, notably cephalopods, use a jet to propel themselves in water. Similarly, a jet engine as it name suggests, emits a jet used to propel rockets, aircraft, jetboats, and submarines.
Famous quotes containing the word jet:
“But every jet of chaos which threatens to exterminate us is convertible by intellect into wholesome force. Fate is unpenetrated causes.”
—Ralph Waldo Emerson (1803–1882)