A jet is a stream of

fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear ...

that is projected into a surrounding medium, usually from some kind of a

nozzle A nozzle is a device designed to control the direction or characteristics of a fluid flow (specially to increase velocity) as it exits (or enters) an enclosed chamber or pipe. A nozzle is often a pipe or tube of varying cross sectional area, ...

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...

or orifice. Jets can travel long distances without dissipating. Jet fluid has higher

momentum In Newtonian mechanics, momentum (more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass ...

compared to the surrounding fluid medium. In the case that the surrounding medium is assumed to be made up of the same fluid as the jet, and this fluid has a

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the int ...

, the surrounding fluid is carried along with the jet in a process called

entrainment Entrainment may refer to: * Air entrainment, the intentional creation of tiny air bubbles in concrete * Brainwave entrainment, the practice of entraining one's brainwaves to a desired frequency * Entrainment (biomusicology), the synchronization of ...

. Some animals, notably

cephalopods A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, a ...

, move by jet propulsion, as do

rocket engine A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accorda ...

s and

jet engine A jet engine is a type of reaction engine discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include Rocket engine, rocket, Pump-jet, water jet, and ...

Applications

Liquid jets are used in many different areas. In everyday life, you can find them for instance coming from the water tap, the

showerhead A shower is a place in which a person bathes under a spray of typically warm or hot water. Indoors, there is a drain in the floor. Most showers have temperature, spray pressure and adjustable showerhead nozzle. The simplest showers have a ...

, and from spray cans. In agriculture, they play a role in

irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been devel ...

and in the application of crop protection products. In the field of medicine, you can find liquid jets for example in injection procedures or

inhalers An inhaler (also known as a puffer, pump or allergy spray) is a medical device used for delivering medicines into the lungs through the work of a person's breathing. This allows medicines to be delivered to and absorbed in the lungs, which prov ...

. Industry uses liquid jets for waterjet cutting, for coating materials or in cooling towers. Atomized liquid jets are essential for the efficiency of

internal combustion engines An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combust ...

. But they also play a crucial role in research, for example in the study of

proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

, phase transitions, extreme states of matter, laser plasmas, High harmonic generation, and also in

particle physics Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...

experiments. Also some animals, notably

, move by jet propulsion. Gas jets are found in

s and

s. Microscopic liquid jets have been studied for their potential application in noninvasive transdermal drug delivery.

References

* Pijush K. Kundu and Ira M. Cohen, "Fluid mechanics, Volume 10", Elsevier, Burlington, MA,USA (2008), * Fluid dynamics {{Fluiddynamics-stub

Applications

See also

References