# Hydraulic engineering

Last updated

Hydraulic engineering as a sub-discipline of civil engineering is concerned with the flow and conveyance of fluids, principally water and sewage. One feature of these systems is the extensive use of gravity as the motive force to cause the movement of the fluids. This area of civil engineering is intimately related to the design of bridges, dams, channels, canals, and levees, and to both sanitary and environmental engineering.

## Contents

Hydraulic engineering is the application of the principles of fluid mechanics to problems dealing with the collection, storage, control, transport, regulation, measurement, and use of water. [1] Before beginning a hydraulic engineering project, one must figure out how much water is involved. The hydraulic engineer is concerned with the transport of sediment by the river, the interaction of the water with its alluvial boundary, and the occurrence of scour and deposition. [1] "The hydraulic engineer actually develops conceptual designs for the various features which interact with water such as spillways and outlet works for dams, culverts for highways, canals and related structures for irrigation projects, and cooling-water facilities for thermal power plants." [2]

## Fundamental principles

A few examples of the fundamental principles of hydraulic engineering include fluid mechanics, fluid flow, behavior of real fluids, hydrology, pipelines, open channel hydraulics, mechanics of sediment transport, physical modeling, hydraulic machines, and drainage hydraulics.

### Fluid mechanics

Fundamentals of Hydraulic Engineering defines hydrostatics as the study of fluids at rest. [1] In a fluid at rest, there exists a force, known as pressure, that acts upon the fluid's surroundings. This pressure, measured in N/m2, is not constant throughout the body of fluid. Pressure, p, in a given body of fluid, increases with an increase in depth. Where the upward force on a body acts on the base and can be found by the equation:

${\displaystyle p=\rho gy}$

where,

ρ = density of water
g = specific gravity
y = depth of the body of liquid

Rearranging this equation gives you the pressure head p/ρg = y. Four basic devices for pressure measurement are a piezometer, manometer, differential manometer, Bourdon gauge, as well as an inclined manometer. [1]

As Prasuhn states:

On undisturbed submerged bodies, pressure acts along all surfaces of a body in a liquid, causing equal perpendicular forces in the body to act against the pressure of the liquid. This reaction is known as equilibrium. More advanced applications of pressure are that on plane surfaces, curved surfaces, dams, and quadrant gates, just to name a few. [1]

### Behavior of real fluids

#### Real and Ideal fluids

The main difference between an ideal fluid and a real fluid is that for ideal flow p1 = p2 and for real flow p1 > p2. Ideal fluid is incompressible and has no viscosity. Real fluid has viscosity. Ideal fluid is only an imaginary fluid as all fluids that exist have some viscosity.

#### Viscous flow

A viscous fluid will deform continuously under a shear force by the pascles law, whereas an ideal fluid does not deform.

#### Laminar flow and turbulence

The various effects of disturbance on a viscous flow are a stable, transition and unstable.

#### Bernoulli's equation

For an ideal fluid, Bernoulli's equation holds along streamlines.

p/ρg + u²/2g = p1/ρg + u1²/2g = p2g + u2²/2g

#### Boundary layer

Assuming a flow is bounded on one side only, and that a rectilinear flow passing over a stationary flat plate which lies parallel to the flow, the flow just upstream of the plate has a uniform velocity. As the flow comes into contact with the plate, the layer of fluid actually 'adheres' to a solid surface. There is then a considerable shearing action between the layer of fluid on the plate surface and the second layer of fluid. The second layer is therefore forced to decelerate (though it is not quite brought to rest), creating a shearing action with the third layer of fluid, and so on. As the fluid passes further along with the plate, the zone in which shearing action occurs tends to spread further outwards. This zone is known as the 'boundary layer'. The flow outside the boundary layer is free of shear and viscous-related forces so it is assumed to act as an ideal fluid. The intermolecular cohesive forces in a fluid are not great enough to hold fluid together. Hence a fluid will flow under the action of the slightest stress and flow will continue as long as the stress is present. [3] The flow inside the layer can be either vicious or turbulent, depending on Reynolds number. [1]

## Applications

Common topics of design for hydraulic engineers include hydraulic structures such as dams, levees, water distribution networks including both domestic and fire water supply, distribution and automatic sprinkler systems, water collection networks, sewage collection networks, storm water management, sediment transport, and various other topics related to transportation engineering and geotechnical engineering. Equations developed from the principles of fluid dynamics and fluid mechanics are widely utilized by other engineering disciplines such as mechanical, aeronautical and even traffic engineers.

Related branches include hydrology and rheology while related applications include hydraulic modeling, flood mapping, catchment flood management plans, shoreline management plans, estuarine strategies, coastal protection, and flood alleviation.

## History

### Antiquity

Earliest uses of hydraulic engineering were to irrigate crops and dates back to the Middle East and Africa. Controlling the movement and supply of water for growing food has been used for many thousands of years. One of the earliest hydraulic machines, the water clock was used in the early 2nd millennium BC. [4] Other early examples of using gravity to move water include the Qanat system in ancient Persia and the very similar Turpan water system in ancient China as well as irrigation canals in Peru. [5]

In ancient China, hydraulic engineering was highly developed, and engineers constructed massive canals with levees and dams to channel the flow of water for irrigation, as well as locks to allow ships to pass through. Sunshu Ao is considered the first Chinese hydraulic engineer. Another important Hydraulic Engineer in China, Ximen Bao was credited of starting the practice of large scale canal irrigation during the Warring States period (481 BC-221 BC), even today hydraulic engineers remain a respectable position in China. Before becoming General Secretary of the Communist Party of China in 2002, Hu Jintao was a hydraulic engineer and holds an engineering degree from Tsinghua University

In the Archaic epoch of the Philippines, hydraulic engineering also developed specially in the Island of Luzon, the Ifugaos of the mountainous region of the Cordilleras built irrigations, dams and hydraulic works and the famous Banaue Rice Terraces as a way for assisting in growing crops around 1000 BC. [6] These Rice Terraces are 2,000-year-old terraces that were carved into the mountains of Ifugao in the Philippines by ancestors of the indigenous people. The Rice Terraces are commonly referred to as the "Eighth Wonder of the World". [7] [8] [9] It is commonly thought that the terraces were built with minimal equipment, largely by hand. The terraces are located approximately 1500 metres (5000 ft) above sea level. They are fed by an ancient irrigation system from the rainforests above the terraces. It is said that if the steps were put end to end, it would encircle half the globe. [10]

Eupalinos of Megara, was an ancient Greek engineer who built the Tunnel of Eupalinos on Samos in the 6th century BC, an important feat of both civil and hydraulic engineering. The civil engineering aspect of this tunnel was the fact that it was dug from both ends which required the diggers to maintain an accurate path so that the two tunnels met and that the entire effort maintained a sufficient slope to allow the water to flow.

Hydraulic engineering was highly developed in Europe under the aegis of the Roman Empire where it was especially applied to the construction and maintenance of aqueducts to supply water to and remove sewage from their cities. [3] In addition to supplying the needs of their citizens they used hydraulic mining methods to prospect and extract alluvial gold deposits in a technique known as hushing, and applied the methods to other ores such as those of tin and lead.

In the 15th century, the Somali Ajuran Empire was the only hydraulic empire in Africa. As a hydraulic empire, the Ajuran State monopolized the water resources of the Jubba and Shebelle Rivers. Through hydraulic engineering, it also constructed many of the limestone wells and cisterns of the state that are still operative and in use today. The rulers developed new systems for agriculture and taxation, which continued to be used in parts of the Horn of Africa as late as the 19th century. [11]

Further advances in hydraulic engineering occurred in the Muslim world between the 8th to 16th centuries, during what is known as the Islamic Golden Age. Of particular importance was the 'water management technological complex' which was central to the Islamic Green Revolution and, [12] by extension, a precondition for the emergence of modern technology. [13] The various components of this 'toolkit' were developed in different parts of the Afro-Eurasian landmass, both within and beyond the Islamic world. However, it was in the medieval Islamic lands where the technological complex was assembled and standardized, and subsequently diffused to the rest of the Old World. [14] Under the rule of a single Islamic Caliphate, different regional hydraulic technologies were assembled into "an identifiable water management technological complex that was to have a global impact." The various components of this complex included canals, dams, the qanat system from Persia, regional water-lifting devices such as the noria, shaduf and screwpump from Egypt, and the windmill from Islamic Afghanistan. [14] Other original Islamic developments included the saqiya with a flywheel effect from Islamic Spain, [15] the reciprocating suction pump [16] [17] [18] and crankshaft-connecting rod mechanism from Iraq, [19] [20] the geared and hydropowered water supply system from Syria, [21] and the water purification methods of Islamic chemists. [22]

### Modern times

In many respects, the fundamentals of hydraulic engineering have not changed since ancient times. Liquids are still moved for the most part by gravity through systems of canals and aqueducts, though the supply reservoirs may now be filled using pumps. The need for water has steadily increased from ancient times and the role of the hydraulic engineer is a critical one in supplying it. For example, without the efforts of people like William Mulholland the Los Angeles area would not have been able to grow as it has because it simply does not have enough local water to support its population. The same is true for many of our world's largest cities. In much the same way, the central valley of California could not have become such an important agricultural region without effective water management and distribution for irrigation. In a somewhat parallel way to what happened in California, the creation of the Tennessee Valley Authority (TVA) brought work and prosperity to the South by building dams to generate cheap electricity and control flooding in the region, making rivers navigable and generally modernizing life in the region.

Leonardo da Vinci (1452–1519) performed experiments, investigated and speculated on waves and jets, eddies and streamlining. Isaac Newton (1642–1727) by formulating the laws of motion and his law of viscosity, in addition to developing the calculus, paved the way for many great developments in fluid mechanics. Using Newton's laws of motion, numerous 18th-century mathematicians solved many frictionless (zero-viscosity) flow problems. However, most flows are dominated by viscous effects, so engineers of the 17th and 18th centuries found the inviscid flow solutions unsuitable, and by experimentation they developed empirical equations, thus establishing the science of hydraulics. [3]

Late in the 19th century, the importance of dimensionless numbers and their relationship to turbulence was recognized, and dimensional analysis was born. In 1904 Ludwig Prandtl published a key paper, proposing that the flow fields of low-viscosity fluids be divided into two zones, namely a thin, viscosity-dominated boundary layer near solid surfaces, and an effectively inviscid outer zone away from the boundaries. This concept explained many former paradoxes and enabled subsequent engineers to analyze far more complex flows. However, we still have no complete theory for the nature of turbulence, and so modern fluid mechanics continues to be combination of experimental results and theory. [23]

The modern hydraulic engineer uses the same kinds of computer-aided design (CAD) tools as many of the other engineering disciplines while also making use of technologies like computational fluid dynamics to perform the calculations to accurately predict flow characteristics, GPS mapping to assist in locating the best paths for installing a system and laser-based surveying tools to aid in the actual construction of a system.

3M Novec 73DE is intended for hardcore fume degreasing, inundation cleaning, or oil testimony; including high dissolvability, low surface strain, non-combustibility, and liquid solidness.

## Related Research Articles

In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics and hydrodynamics. Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation.

In fluid dynamics, laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mixing, and adjacent layers slide past one another like playing cards. There are no cross-currents perpendicular to the direction of flow, nor eddies or swirls of fluids. In laminar flow, the motion of the particles of the fluid is very orderly with particles close to a solid surface moving in straight lines parallel to that surface. Laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection.

Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the ambient pressure.

Rheology is the study of the flow of matter, primarily in a liquid or gas state, but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force. Rheology is a branch of physics, and it is the science that deals with the deformation and flow of materials, both solids and liquids.

Hydraulics is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counterpart of pneumatics, which concerns gases. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the applied engineering using the properties of fluids. In its fluid power applications, hydraulics is used for the generation, control, and transmission of power by the use of pressurized liquids. Hydraulic topics range through some parts of science and most of engineering modules, and cover concepts such as pipe flow, dam design, fluidics and fluid control circuitry. The principles of hydraulics are in use naturally in the human body within the vascular system and erectile tissue. Free surface hydraulics is the branch of hydraulics dealing with free surface flow, such as occurring in rivers, canals, lakes, estuaries and seas. Its sub-field open-channel flow studies the flow in open channels.

Fluid bearings are bearings in which the load is supported by a thin layer of rapidly moving pressurized liquid or gas between the bearing surfaces. Since there is no contact between the moving parts, there is no sliding friction, allowing fluid bearings to have lower friction, wear and vibration than many other types of bearings. Thus, it is possible for some fluid bearings to have near-zero wear if operated correctly.

Permeability in fluid mechanics and the Earth sciences is a measure of the ability of a porous material to allow fluids to pass through it.

Soil mechanics is a branch of soil physics and applied mechanics that describes the behavior of soils. It differs from fluid mechanics and solid mechanics in the sense that soils consist of a heterogeneous mixture of fluids and particles but soil may also contain organic solids and other matter. Along with rock mechanics, soil mechanics provides the theoretical basis for analysis in geotechnical engineering, a subdiscipline of civil engineering, and engineering geology, a subdiscipline of geology. Soil mechanics is used to analyze the deformations of and flow of fluids within natural and man-made structures that are supported on or made of soil, or structures that are buried in soils. Example applications are building and bridge foundations, retaining walls, dams, and buried pipeline systems. Principles of soil mechanics are also used in related disciplines such as geophysical engineering, coastal engineering, agricultural engineering, hydrology and soil physics.

The electronic–hydraulic analogy is the most widely used analogy for "electron fluid" in a metal conductor. Since electric current is invisible and the processes in play in electronics are often difficult to demonstrate, the various electronic components are represented by hydraulic equivalents. Electricity was originally understood to be a kind of fluid, and the names of certain electric quantities are derived from hydraulic equivalents. As with all analogies, it demands an intuitive and competent understanding of the baseline paradigms.

The history of fluid mechanics, the study of how fluids move and the forces on them, dates back to the Ancient Greeks.

Fluid mechanics is the branch of physics concerned with the mechanics of fluids and the forces on them. It has applications in a wide range of disciplines, including mechanical, civil, chemical and biomedical engineering, geophysics, oceanography, meteorology, astrophysics, and biology.

Turbulence modeling is the construction and use of a mathematical model to predict the effects of turbulence. Turbulent flows are commonplace in most real life scenarios, including the flow of blood through the cardiovascular system, the airflow over an aircraft wing, the re-entry of space vehicles, besides others. In spite of decades of research, there is no analytical theory to predict the evolution of these turbulent flows. The equations governing turbulent flows can only be solved directly for simple cases of flow. For most real life turbulent flows, CFD simulations use turbulent models to predict the evolution of turbulence. These turbulence models are simplified constitutive equations that predict the statistical evolution of turbulent flows.

In fluid flow, friction loss is the loss of pressure or “head” that occurs in pipe or duct flow due to the effect of the fluid's viscosity near the surface of the pipe or duct. In mechanical systems such as internal combustion engines, the term refers to the power lost in overcoming the friction between two moving surfaces, a different phenomenon.

In hydraulic engineering, a nappe is a sheet or curtain of water that flows over a weir or dam. The upper and lower water surface have well-defined characteristics that are created by the crest of a dam or weir. Both structures have different features that characterize how a nappe might flow through or over impervious concrete structures. Hydraulic engineers distinguish these two water structures in characterizing and calculating the formation of a nappe. Engineers account for the bathymetry of standing bodies or moving bodies of water. An appropriate crest is built for the dam or weir so that dam failure is not caused by nappe vibration or air cavitation from free-overall structures.

A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter, and is the only state with a definite volume but no fixed shape. A liquid is made up of tiny vibrating particles of matter, such as atoms, held together by intermolecular bonds. Like a gas, a liquid is able to flow and take the shape of a container. Most liquids resist compression, although others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of the liquid state is surface tension, leading to wetting phenomena. Water is, by far, the most common liquid on Earth.

Hubert Chanson is a hydraulic engineering and applied fluid mechanics academic. Since 1990 he has worked at the University of Queensland.

The Reynolds number helps predict flow patterns in different fluid flow situations. At low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers flows tend to be turbulent. The turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow. These eddy currents begin to churn the flow, using up energy in the process, which for liquids increases the chances of cavitation. Reynolds numbers are an important dimensionless quantity in fluid mechanics.

The viscous stress tensor is a tensor used in continuum mechanics to model the part of the stress at a point within some material that can be attributed to the strain rate, the rate at which it is deforming around that point.

An aqueduct is a watercourse constructed to carry water from a source to a distribution point far away. In modern engineering, the term aqueduct is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose. The term aqueduct also often refers specifically to a bridge carrying an artificial watercourse. Aqueducts were used in ancient Greece, ancient Egypt, and ancient Rome. In modern times, the largest aqueducts of all have been built in the United States to supply large cities. The simplest aqueducts are small ditches cut into the earth. Much larger channels may be used in modern aqueducts. Aqueducts sometimes run for some or all of their path through tunnels constructed underground. Modern aqueducts may also use pipelines. Historically, agricultural societies have constructed aqueducts to irrigate crops and supply large cities with drinking water.

Biofluid dynamics may be considered as the discipline of biological engineering or biomedical engineering in which the fundamental principles of fluid dynamics are used to explain the mechanisms of biological flows and their interrelationships with physiological processes, in health and in diseases/disorder. It can be considered as the conjuncture of mechanical engineering and biological engineering. It spans from cells to organs, covering diverse aspects of the functionality of systemic physiology, including cardiovascular, respiratory, reproductive, urinary, musculoskeletal and neurological systems etc. Biofluid dynamics and its simulations in computational fluid dynamics (CFD) apply to both internal as well as external flows. Internal flows such as cardiovascular blood flow and respiratory airflow, and external flows such as flying and aquatic locomotion. Biological fluid Dynamics involves the study of the motion of biological fluids. It can be either circulatory system or respiratory systems. Understanding the circulatory system is one of the major areas of research. The respiratory system is very closely linked to the circulatory system and is very complex to study and understand. The study of Biofluid Dynamics is also directed towards finding solutions to some of the human body related diseases and disorders. The usefulness of the subject can also be understood by seeing the use of Biofluid Dynamics in the areas of physiology in order to explain how living things work and about their motions, in developing an understanding of the origins and development of various diseases related to human body and diagnosing them, in finding the cure for the diseases related to cardiovascular and pulmonary systems.

## References

1. Prasuhn, Alan L. Fundamentals of Hydraulic Engineering. Holt, Rinehart, and Winston: New York, 1987.
2. Cassidy, John J., Chaudhry, M. Hanif, and Roberson, John A. "Hydraulic Engineering", John Wiley & Sons, 1998
3. E. John Finnemore, Joseph Franzini "Fluid Mechanics with Engineering Applications", McGraw-Hill,2002
4. Gascoigne, Bamber. “History of Clocks”. History World. From 2001, ongoing. http://www.historyworld.net/wrldhis/PlainTextHistories.asp?groupid=2322&HistoryID=ac08&gtrack=pthc
5. "Qanats" Water History. From 2001, ongoing. http://www.waterhistory.org/histories/qanats/
6. Filipinasoul.com.‘The Best’ of the Philippines - its natural wonders Archived 2014-11-05 at the Wayback Machine
7. National Statistical Coordinating Body of the Philippines. FACTS & FIGURES:Ifugao province Archived 2012-11-13 at the Wayback Machine
8. About Banaue > Tourist Attractions Archived 2008-12-14 at the Wayback Machine
9. Department of Tourism: Ifugao Province Archived 2009-03-02 at the Wayback Machine . Accessed September 04, 2008.
10. Njoku, Raphael Chijioke (2013). The History of Somalia. p. 26. ISBN   9780313378577 . Retrieved 2014-02-14.
11. Edmund Burke (June 2009), "Islam at the Center: Technological Complexes and the Roots of Modernity", Journal of World History , University of Hawaii Press, 20 (2): 165–186 [174], doi:10.1353/jwh.0.0045, S2CID   143484233
12. Edmund Burke (June 2009), "Islam at the Center: Technological Complexes and the Roots of Modernity", Journal of World History , University of Hawaii Press, 20 (2): 165–186 [168], doi:10.1353/jwh.0.0045, S2CID   143484233
13. Edmund Burke (June 2009), "Islam at the Center: Technological Complexes and the Roots of Modernity", Journal of World History , University of Hawaii Press, 20 (2): 165–186 [168 & 173], doi:10.1353/jwh.0.0045, S2CID   143484233
14. Ahmad Y Hassan, Flywheel Effect for a Saqiya Archived 2010-10-07 at the Wayback Machine .
15. Donald Routledge Hill, "Mechanical Engineering in the Medieval Near East", Scientific American, May 1991, pp. 64–9. (cf. Donald Routledge Hill, Mechanical Engineering Archived 2007-12-25 at the Wayback Machine )
16. Ahmad Y Hassan. "The Origin of the Suction Pump: Al-Jazari 1206 A.D." Archived from the original on 2008-02-26. Retrieved 2008-07-16.
17. Donald Routledge Hill (1996), A History of Engineering in Classical and Medieval Times, Routledge, pp. 143 & 150-2
18. Sally Ganchy, Sarah Gancher (2009), Islam and Science, Medicine, and Technology, The Rosen Publishing Group, p.  41, ISBN   978-1-4358-5066-8
19. Howard R. Turner (1997), Science in Medieval Islam: An Illustrated Introduction, p. 181, University of Texas Press, ISBN   0-292-78149-0
20. Levey, M. (1973), ‘ Early Arabic Pharmacology’, E. J. Brill; Leiden
21. Fluid Mechanics
• Vincent J. Zipparro, Hans Hasen (Eds), Davis' Handbook of Applied Hydraulics, Mcgraw-Hill, 4th Edition (1992), ISBN   0070730024, at Amazon.com
• Classification of Organics in Secondary Effluents. M. Rebhun, J. Manka. Environmental Science and Technology, 5, pp. 606–610, (1971). 25.