The siphon

Описание: A siphon is a pipe connecting two reservoirs of different water levels, in which the liquid pressure in the pipe would locally become less than atmospheric. In the siphon, the liquid flows from the upper reservoir to the lower reservoir. In the process, the siphon lifts the liquid up to an elevation higher than the surface of the upper reservoir. That is, the fluid goes upwards until a maximum elevation where the pressure is sub-atmospheric, before discharging into the lower reservoir.
An application is the siphon spillway. Indeed, the siphon principle may be applied to spillway design (Ervine 1976, Novak et al. 2007). Key features and advantages of a siphon spillway include a relatively high discharge per unit width, passing the flood with an almost constant water level, and an absence of mechanical and moving parts. On another hand, the operation of siphon spillways may be adversely affected by the risks of siphon entrance blockage, the presence of sub-atmospheric pressures, the instabilities during the priming process, and the danger of sudden surges of water released downstream of the dam.
Related hydraulic structures include the inverted siphon and the air-regulated siphon, which will be discussed in other video movies. The former, the inverted siphon, is basically a pipe connecting two reservoirs, in which the pressure is always greater than atmospheric. Inverted siphons have been used since Antiquity, and magnificent structures included the inverted siphon on the Roman aqueduct at Aspendos (Turkey) and the inverted siphon at Beaunant along the Roman aqueduct at Gier (France). The latter, the air-regulated siphon, is a recent development which allows amounts of air into the siphon during the priming, ensuring a smooth, gradual, controlled priming action, and more controlled siphon spillway operation and downstream flood release.
The operation of siphons and siphon spillways constitute a basic application of fluid mechanics to open channel hydraulics and hydraulic structures. This is further discussed in a number of relevant Youtube video movies in the same channel at: {   / @hubert_chanson  }
 
Hydraulic Engineering and Applied Hydrodynamics in Hubert Chanson Youtube channel {   / @hubert_chanson  }
Fundamentals of open channel hydraulics [Playlist]
Advanced hydraulics of open channel flow [Playlist]
Hydraulic structures [Playlist]

The Equation of Conservation of Mass in Fluid Mechanics {   • The Equation of Conservation of Mass in Fl...  }
Equation of conservation of energy in fluid mechanics {   • Equation of conservation of energy in flui...  }

The siphon {   • The siphon  }
The inverted siphon {   • The inverted siphon  }
The air-regulated siphon {   • The air-regulated siphon  }
Application of the energy equation to a siphon spillway {   • Application of the energy equation to a si...  }

Acknowledgements
Late Prof. Alan ERVINE
Jason VAN DER GEVEL
Los Angeles Public Library

References
ERVINE, D.A. (1976). "The Design and Modelling of Air-Regulated Siphon Spillways." Proceedings of the Institution Civil Engineers, London, Part 2, June 1976, 61, pp. 383-400.
STREETER, V.L., and WYLIE, E.B. (1981). "Fluid Mechanics." McGraw-Hill, 1st SI Metric edition, Singapore.
CHANSON, H. (2004). "The Hydraulics of Open Channel Flow: An Introduction." Butterworth-Heinemann, 2nd edition, Oxford, UK, 630 pages (ISBN 978 0 7506 5978 9).
NOVAK, P., MOFFAT, A.I.B., NALLURI, C., and NARAYANAN, R. (2007). "Hydraulic Structures." Taylor & Francis, London, UK, 4th edition, 700 pages.