Hydraulics (redirected from Hydraulic pressure)

hydraulics, branch of engineering concerned mainly with moving liquids. The term is applied commonly to the study of the mechanical properties of water, other liquids, and even gases when the effects of compressibility are small. Hydraulics can be divided into two areas, hydrostatics and hydrokinetics. Hydrostatics, the consideration of liquids at rest, involves problems of buoyancy and flotation, pressure on dams and submerged devices, and hydraulic presses. The relative incompressibility of liquids is one of its basic principles. Hydrodynamics, the study of liquids in motion, is concerned with such matters as friction and turbulence generated in pipes by flowing liquids, the flow of water over weirs and through nozzles, and the use of hydraulic pressure in machinery.

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hydraulics

Branch of science concerned with the practical applications of fluids, primarily liquids, in motion. It is related to fluid mechanics, which in large part provides its theoretical foundation. Hydraulics deals with such matters as the flow of liquids in pipes, rivers, and channels and their confinement by dams and tanks. Some of its principles apply also to gases, usually when variations in density are relatively small. The scope of hydraulics extends to such mechanical devices as actuators and control systems. See also Bernoulli's principle, Pascal's law, pump.

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Hydraulics

The branch of engineering that focuses on the practical problems of collecting, storing, measuring, transporting, controlling, and using water and other liquids. It differs from fluid mechanics, which is more theoretical and includes the study of gases as well as liquids; and from hydrology, which is the study of the properties, distribution, and circulation of the Earth's water.

Many problems in hydraulics involve pipe flow. Pipe flow occurs in the direction of decreasing energy. The primary forms of energy in pipes are position energy (height of the fluid), pressure energy, and kinetic energy according to Bernoulli's theorem. Fluids can be forced to flow uphill if the pressure energy and kinetic energy are large enough to overcome the position energy. This can be accomplished with a pump that adds pressure energy to the fluid. See Pump

Liquids in motion produce forces whenever the velocity or flow direction changes. For example, forces develop at the nozzle of a fire hose, at pipe bends, and when flowing water is used to turn a turbine. The force is generally proportional to the flow rate, the mass density, and the velocity change.

Liquids are often transported in open channels instead of pipes. An energy imbalance produces flow in open channels, just as it does in pipes. The primary forms of energy are position energy, flow depth, and kinetic energy. Energy balance methods are used to solve many problems in gradually varied flow (that is, the depth changes slowly over short distances), but a momentum balance is required for rapidly varied flow.

Hydraulic principles apply to many other scientific and engineering endeavors. For example, ground-water flow is studied in geology but is governed by the principles of hydraulics. Coastal hydraulics is an important subset of oceanography. The design of certain structures, such as jetties, dams, spillways, locks, piers, levees, dry docks, and tanks, requires an understanding of hydraulic concepts. Scale models are often used to better understand some of the complex forces and currents associated with these large structures. See Coastal engineering, Dam, River engineering