Search results for "hydraulic structure"
showing 10 items of 10 documents
Dimensional analysis and stage-discharge relationship for weirs: a review
2017
Deducing the weir flow stage-discharge relationship is a classical hydraulic problem. In this regard Buckingham’s theorem of dimensional analysis can be used to find simple and accurate formulas to obtain the rating curves of different weir types. At first, in this review paper the rectangular weir that is a very common hydraulic structure is studied. It is indicated that the crest shape, approach channel width, obliquity (angle between the weir crest and the direction normal to the flow motion) and vertical inclination (pivot weir) are the key-parameters affecting the flow over the rectangular weirs. The flow over the triangular, labyrinth, parabolic, circular, elliptical, and W-weirs are …
New Solution of Classical Hydraulic Jump
2009
This technical note, applying dimensional analysis and incomplete self-similarity, proposes a new functional relationship for the sequent depth ratio for hydraulic jumps over both smooth and rough horizontal beds. For the smooth bed condition, experimental measurements in the literature were used to calibrate the new relationship. For the rough bed condition the data of a previous investigation were used with new measurements carried out in a rectangular horizontal flume having a gravel bed. Finally, a generalized solution of the sequent depth ratio is proposed.
Laminated carbonate deposits in Roman aqueducts: Origin, processes and implications
2013
Carbonate deposits in Roman aqueducts of Patara and Aspendos (southern Turkey) were studied to analyse the nature of their regular layering. Optical microscopy and electron-backscattered diffraction results show an alternation of dense, coarsely crystalline, translucent laminae composed of bundles and fans of elongate calcite crystals with their c-axes parallel to the long axis, and porous, fine-grained laminae with crystals at near-random orientation. The ?18O and ?13C data show a strong cyclicity and anti-correlation, whereby high and low ?18O values correspond to dense columnar and porous fine-grained laminae, respectively. Geochemical analyses show similar cyclic changes in carbonate co…
Identifying a dominant discharge for natural rivers in southern Italy
2012
Abstract Natural rivers are subjected to continuous adjustments in response to any change in the environment. These environmental changes may occur naturally, as in the case of climatic variation or changes in vegetative cover, or may be related to human activities including channelization, damming, bank protection, and bridge construction. Identifying the value of that discharge (‘dominant’ or ‘effective’ discharge, QD) considered responsible for the main changes operated by a river has been a subject of great challenge to scientists and engineers during the last decades. In fact, this threshold value is largely adopted for stream-management decisions, for predicting the stable slope upstr…
Coastal Development of Daugavgrîva Island, Located Near the Gulf of Riga / Rîgas Lîèa Piekrastes Krasta Attîstîba Daugavgrîvas Salâ
2015
Abstract Natural as well as anthropogenic processes impact greatly sensitive coastal areas all over the world. The spectrum of natural processes involved can be classified as meteorological, geological, marine, and lithodynamic. The Baltic Sea with its Gulf of Riga is an area in which combined sea erosion and accumulation processes, as well as alluvial processes, play significant roles in the coastal development. Major anthropogenic processes include impacts from ports and coastal protection structures, such as Riga Port hydraulic structures, fairway channels and coastal defence items. During summer also additional pressure of recreational activities has increased the effect on the coastal …
Experimental observation of horizontal coherent turbulent structures in a straight flume
2009
The present paper describes results of laboratory experiments carried out to investigate the evolution of horizontal coherent turbulent structures for different roughness conditions of channel walls. The occurrence of turbulent events (inward interaction, ejection, sweep and burst) is identified through the conditioned quadrant analysis. The filtered data set is used to determine the probability density distribution of each turbulent event. Particular attention is focused on sweep and ejection events and peculiar maps showing the distributions of the horizontal Reynolds shear stress, for each examined experimental condition, are also presented and discussed.
Bed scouring downstream of hydraulic structures under steady flow conditions: Experimental analysis of space and time scales and implications for mat…
2011
Abstract Sediment transport and bed deformation in alluvial rivers are space and time dependent. The knowledge of the space and time scales can be helpful for the definition of predictive procedures of an alluvial reach response to changing boundary conditions. In this work, attention is paid to scouring process occurring downstream of the rigid basement of a hydraulic structure. The analysis is focused on transient bed profiles which are determined, under steady flow conditions, by a decrease of the upstream sediment transport rate. In particular, the paper is aimed at improving understanding of the space and time scales required by the alluvial system to reach the equilibrium conditions. …
New stage-discharge relationship for cylindrical and semi-cylindrical edged sluice gates
2019
Abstract Gates are simple hydraulic structures which have been widely used for flow control and measurement in irrigation networks. In this paper new sluice gates with cylindrical and semi-cylindrical edges were introduced and the flow movement below these types of gates was experimentally investigated for both free- and submerged-flow conditions. The Buckingham theorem of dimensional analysis and the self-similarity theory were applied for developing the stage-discharge relationships for the two investigated flow conditions. For these cylindrical and semi-cylindrical edged gates and a free-flow condition, the proposed stage-discharge relationship was characterized by an estimate error less…