Auteur Willi H. Hager
Documents disponibles écrits par cet auteur (15)
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Oscar Castro-Orgaz, Auteur ; Willi H. Hager, Auteur |The dynamics of free surface flow is characterised by the so-called Froude number F, whose value F = 1 separates subcritical (F < 1) and supercritical (F > 1) flows. The transition from F < 1 to F > 1 is smooth and continuous, as observed in[...]
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Oscar Castro-Orgaz, Auteur ; Willi H. Hager, Auteur |Flows from mild to steep slopes are relevant in hydraulic engineering relating to chute spillways and slope changes in irrigation networks. These flows are associated with transitional flow from sub- to supercritical conditions, smooth curviline[...]
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Michael Pfister, Auteur ; Willi H. Hager, Auteur |Free jets issued at the end of chutes may be generated rather with deflectors than with flip buckets. The latter jet trajectories were previously investigated, using the standard approach based on the take-off angle. However, few information con[...]
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Michael Pfister, Auteur ; Willi H. Hager, Auteur |Jets generated at chute ends move a potential scour zone away from the dam, and dissipate flow energy to reduce the scour. Usually, so-called flip buckets or ski jumps are provided to generate jets, yet they are rarely issued by deflectors. The [...]
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Willi H. Hager, Auteur |The Gauckler-Manning-Strickler GMS formula is currently often applied to determine uniform flow in open channels and flow in closed conduits. The present historical paper aims to describe this formula and to give a biography of Philippe-Gaspard [...]
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Willi H. Hager, Auteur ; Uno Liiv, Auteur |Hydraulic engineers are familiar with the Nikuradse sand-roughened pipes, the ‘Nikuradse harp’ describing the friction coefficient of pipe flow, and the Nikuradse plots showing data points almost perfectly arranged along a curve. Who was Nikurad[...]
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Oscar Castro-Orgaz, Auteur ; Willi H. Hager, Auteur |Joseph Valentin Boussinesq (1842–1929) is known in open channel hydraulics for the outstanding theory bearing his name to deal with streamlined-flows. However, the original developments did not last over time and remain lost in his original writ[...]
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Lukas Schmocker, Auteur ; Willi H. Hager, Auteur |Dikes along rivers protect a valley and its people and property from floods. Recent dike failures due to overtopping highlight the need to understand this damage process. Its accurate prediction is essential to develop effective emergency action[...]
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Oscar Castro-Orgaz, Auteur ; Willi H. Hager, Auteur |Near-critical flows in rivers and natural streams usually present a wavelike undular free surface, associated with dune-type bed-forms. The formation of this particular bed geometry is related to the shear stress acting on the river bed. The bou[...]
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Lukas Schmocker, Auteur ; Willi H. Hager, Auteur |Due to increased flood discharges during the past years, overtopping of dikes and earthen embankments has caused large damages to the surrounding infrastructure and the environment. Despite the numerous dike breaches and the high damage potentia[...]
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Oscar Castro-Orgaz, Auteur ; Willi H. Hager, Auteur |Spatially-varied open channel flows with a streamwise discharge variation occur in the side-weir, side-channel and bottom outlet. The governing equations were formulated in the 1970s by Yen and Wenzel. However, no attempts were made to provide c[...]
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The Journal of Hydraulic Research (JHR) reaches in 2012 the 50th publication year, so that an adequate look back is appropriate. This paper describes the foundations of both the International Association of Hydro-environment Engineering and Rese[...]
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Oscar Castro-Orgaz, Auteur ; Willi H. Hager, Auteur |Turbulent discontinuous open-channel flow appears in practice due to separation zones. The current practice overlooks the separation bubble by neglecting its velocity and by assuming static pressure on the active main stream. Based on the pionee[...]
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Oscar Castro-Orgaz, Auteur ; Willi H. Hager, Auteur |Water flow over short hydraulic transitions is usually modelled by the irrotational flow theory, for which the energy head remains constant over the entire flow domain. Velocity and pressure distributions are then obtained based on the stream an[...]
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Although the Bond number is generally known in fluid mechanics to describe the effects of surface tension and weight of a liquid drop or bubble, W.N. Bond as an individual is currently hardly known. Based on a lucky coincidence, the author was a[...]
