fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasma (physics), plasmas) and the forces on them. Originally applied to water (hydromechanics), it found applications in a wide range of discipl ...

, a splash is a sudden disturbance to the otherwise quiescent

free surface In physics, a free surface is the surface of a fluid that is subject to zero parallel shear stress, such as the interface between two homogeneous fluids. An example of two such homogeneous fluids would be a body of water (liquid) and the air in ...

of a liquid (usually

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

). The disturbance is typically caused by a solid object suddenly hitting the surface, although splashes can occur in which moving liquid supplies the energy. This use of the word is

onomatopoeic Onomatopoeia (or rarely echoism) is a type of word, or the process of creating a word, that phonetically imitates, resembles, or suggests the sound that it describes. Common onomatopoeias in English include animal noises such as ''oink'', '' ...

; in the past, the term "plash" has also been used. Splash also happens when a liquid

droplet A drop or droplet is a small column of liquid, bounded completely or almost completely by free surfaces. A drop may form when liquid accumulates at the end of a tube or other surface boundary, producing a hanging drop called a pendant drop. Dro ...

impacts on a liquid or a solid surface; in this case, a symmetric ''corona'' (resembling a

coronet In British heraldry, a coronet is a type of crown that is a mark of rank of non-reigning members of the royal family and peers. In other languages, this distinction is not made, and usually the same word for ''crown'' is used irrespective of ra ...

) is usually formed as shown in Harold Edgerton's famous milk splash photography, as

milk Milk is a white liquid food produced by the mammary glands of lactating mammals. It is the primary source of nutrition for young mammals (including breastfeeding, breastfed human infants) before they are able to digestion, digest solid food. ...

is opaque. Historically, Worthington (1908) was the first one who systematically investigated the splash dynamics using photographs. Splashes are characterized by transient ballistic flow, and are governed by the

Reynolds number In fluid dynamics, the Reynolds number () is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between Inertia, inertial and viscous forces. At low Reynolds numbers, flows tend to ...

and the

Weber number The Weber number (We) is a dimensionless number in fluid mechanics that is often useful in analysing fluid flows where there is an interface between two different fluids, especially for multiphase flows with strongly curved surfaces. It is named ...

. In the image of a brick splashing into water, one can identify freely moving airborne water droplets, a phenomenon typical of high Reynolds number flows; the intricate non-spherical shapes of the droplets show that the Weber number is high. Also seen are entrained air bubbles in the body of the water, and an expanding ring of disturbance propagating away from the impact site.

Sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

is said to splash if hit sufficiently hard (see dry quicksand) and sometimes the impact of a

meteorite A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical ...

is referred to as splashing, if small bits of ejecta are formed. Physicist Lei Xu and coworkers at the

University of Chicago The University of Chicago (UChicago, Chicago, or UChi) is a Private university, private research university in Chicago, Illinois, United States. Its main campus is in the Hyde Park, Chicago, Hyde Park neighborhood on Chicago's South Side, Chic ...

discovered that the splash due to the impact of a small drop of

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

onto a dry solid surface could be suppressed by reducing the pressure below a specific threshold. For drops of diameter 3.4 mm falling through

air An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

, this pressure was about 20

kilopascal The pascal (symbol: Pa) is the unit of pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pre ...

s, or 0.2

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

. A plate made of a hard material on which a stream of liquid is designed to fall is called a "splash plate". It may serve to protect the ground from

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

by falling water, such as beneath an artificial waterfall or water outlet in soft ground. Splash plates are also part of

spray nozzle A spray nozzle or atomizer is a device that facilitates the dispersion of a liquid by the formation of a Spray (liquid drop), spray. The production of a spray requires the fragmentation of liquid structures, such as liquid sheets or ligaments ...

s, such as in

irrigation sprinkler An irrigation sprinkler (also known as a water sprinkler or simply a sprinkler) is a device used to irrigate (water) agricultural crops, lawns, landscapes, golf courses, and other areas. They are also used for cooling and for the control of airb ...

systems.

References

{{Reflist Fluid dynamics

See also

References