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1
Heller, Valentin, Willi H. Hager i Hans-Erwin Minor. "Ski Jump Hydraulics". Journal of Hydraulic Engineering 131, nr 5 (maj 2005): 347–55. http://dx.doi.org/10.1061/(asce)0733-9429(2005)131:5(347).
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Steiner, Remo, Valentin Heller, Willi H. Hager i Hans-Erwin Minor. "Deflector Ski Jump Hydraulics". Journal of Hydraulic Engineering 134, nr 5 (maj 2008): 562–71. http://dx.doi.org/10.1061/(asce)0733-9429(2008)134:5(562).
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Hotchkiss, Rollin H., Patrick J. Flanagan i Kevin Donahoo. "Hydraulic Jumps in Broken-Back Culverts". Transportation Research Record: Journal of the Transportation Research Board 1851, nr 1 (styczeń 2003): 35–44. http://dx.doi.org/10.3141/1851-04.
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A broken-back culvert has one or more changes in grade within the prismatic barrel profile. One section of a broken-back culvert is usually steep, with the steep slope contributing to high outlet velocities unless a hydraulic jump forms upstream from the culvert outlet. Predictive equations have been published for a wide range of experimental conditions but still do not describe the hydraulics of a jump as it traverses the steeply sloped section and the most downstream section of a broken-back culvert. A computer program, the Broken-Back Culvert Analysis Program (BCAP), analyzes the hydraulics of circular or box-shaped broken-back culverts and provides a comprehensive design tool for engineers. It predicts whether a hydraulic jump will occur and, if so, where it begins and ends. Analyses are performed for 10 discharges. Outputs include rating curves for headwater and outlet depths and outlet velocity and tabulations of hydraulic parameters for each discharge. The water surface profiles throughout the culvert, except through the hydraulic jump, are computed and are plotted on the screen. Experiments were performed with model culverts to assess the accuracy of the predictive equations in BCAP for headwater depth, the location of a hydraulic jump, and the hydraulic jump length. The predictions for the headwater depth at the culvert inlet matched the experimental observations well, but predictions for hydraulic jump location and length were less satisfactory. BCAP has been used for hundreds of design projects in Nebraska and has been downloaded almost 300 times from at least 22 different states. It is recommended that BCAP be improved as better experimental data become available.
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Hager, Willi H. "Classical hydraulic jump: free surface profile". Canadian Journal of Civil Engineering 20, nr 3 (1.06.1993): 536–39. http://dx.doi.org/10.1139/l93-068.
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Based on a large number of experiments, a simple formula is developed for the time-averaged free surface profile of a classical hydraulic jump. This novel approach is based on the length of the roller. The resulting surface profile fits the data well for usual inflow Froude numbers in the range of 2 to 10. Key words: backwater, channel flow, hydraulics, open channel, surface profile.
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Bayon-Barrachina, Arnau, i Petra Amparo Lopez-Jimenez. "Numerical analysis of hydraulic jumps using OpenFOAM". Journal of Hydroinformatics 17, nr 4 (13.03.2015): 662–78. http://dx.doi.org/10.2166/hydro.2015.041.
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The present paper deals with a hydraulic jump study, characterization and numerical modeling. Hydraulic jumps constitute a common phenomenon in the hydraulics of open channels that increases the shear stress on streambeds, so promoting their erosion. A three-dimensional computational fluid dynamics model is proposed to analyze hydraulic jumps in horizontal smooth rectangular prismatic open-air channels (i.e., the so-called classical hydraulic jump). Turbulence is modeled using three widely used Reynolds-averaged Navier–Stokes (RANS) models, namely: Standard k − ɛ, RNG k − ɛ, and SST k − ω. The coexistence of two fluids and the definition of an interface between them are treated using a volume method in Cartesian grids of several element sizes. An innovative way to deal with the outlet boundary condition that allows the size of the simulated domain to be reduced is presented. A case study is conducted for validation purposes (FR1 ∼ 6.10, Re1 ∼ 3.5·105): several variables of interest are computed (sequent depths, efficiency, roller length, free surface profile, etc.) and compared to previous studies, achieving accuracies above 98% in all cases. In the light of the results, the model can be applied to real-life cases of design of hydraulic structures.
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Lauria, Agostino, i Giancarlo Alfonsi. "Numerical Investigation of Ski Jump Hydraulics". Journal of Hydraulic Engineering 146, nr 4 (kwiecień 2020): 04020012. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0001718.
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Godo, Anna M., i J. A. McCorquodale. "Effect of diurnal temperature variation on the hydraulics of clarifiers". Canadian Journal of Civil Engineering 18, nr 6 (1.12.1991): 1084–87. http://dx.doi.org/10.1139/l91-131.
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This study was carried out to obtain data on the behaviour of thermally induced density currents in primary rectangular clarifiers so that better models can be developed for these units. This note deals with the case when the influent is cooler than the ambient temperature in the tank. The experiments were made in a model with a scale of about 1:20 compared to the typical full-scale clarifier. Temperature surveys and dye tests were carried out for turbulent flow and temperature differences between influent and effluent that were equivalent to ±0.2 °C in the prototype on a diurnal basis. The results indicate six flow regimes that follow a decrease in influent temperature: (i) denser wall jet; (ii) splash at the end wall; (iii) moving internal hydraulic jump; (iv) submerged internal hydraulic jump; (v) splash at the influent baffle; and (vi) stratified flow. A comparison of the test data with those available in the literature showed that the entrainment equations involving the Richardson number are adequate for modelling, but the classical hydraulic jump equations need modifications for the effect of entrainment. Key words: clarifiers, rectangular, primary, model, density currents, internal hydraulic jumps, unsteady flow, denser wall jets.
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Dermawan, V., D. R. Dermawan, M. J. Ismoyo i P. H. Wicaksono. "Investigation Of Hydraulic Flow Characteristics On Drop Structures". IOP Conference Series: Earth and Environmental Science 930, nr 1 (1.12.2021): 012028. http://dx.doi.org/10.1088/1755-1315/930/1/012028.
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Abstract Drop structures are required if the slope of the ground level is steeper than the maximum allowable gradient channel. Drop structures become bigger as height increases. Its hydraulic capability may be reduced due to variations of jets falling on the stilling basin floor due to discharge changing. Drop structures should not be used if the change in energy level exceeds 1.50 m. The free-falling overflow on drop structures will hit the stilling basin and move downstream. As a result of overflows and turbulence in the pool below the nappe, some energy is dissipated at the front. The rest of the energy will be reduced downstream. The objectives of this study are to investigate the hydraulics flow behavior in straight and sloping drop structures and to investigate hydraulics flow behavior in a single and serial vertical drop (stepped drop). The hydraulic model results of single and stepped drop structures are compared to obtain flow behavior and energy dissipation information. The comparisons are specific to the flow parameters, including flow depth at the drop structures toe, flow depth after the jump, and hydraulic jump length.
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Stojnic, Ivan, Michael Pfister, Jorge Matos i Anton J. Schleiss. "Plain Stilling Basin Performance below 30° and 50° Inclined Smooth and Stepped Chutes". Water 14, nr 23 (6.12.2022): 3976. http://dx.doi.org/10.3390/w14233976.
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Energy dissipators, such as stilling basins, are usually required at the toe of stepped chutes to achieve adequate and safe operation of the spillway. Stepped chute hydraulics has been extensively studied in last several decades, however, only limited knowledge is available on the stilling basin performance below stepped chutes. In particular, the effect of the chute slope remains unknown, despite being a central design issue. Therefore, an experimental campaign was performed using a 30° or 50° inclined smooth or stepped chute with an adjacent conventional plain stilling basin. The experimental results indicated that, within the stilling basin, the surface characteristics and the roller as well as hydraulic jump lengths are practically independent of the chute slope. This further strengthens the previous findings that stepped chutes require 17% longer dimensionless jump lengths and consequently stilling basin lengths. The experimental results also confirmed that stepped chutes generated increased extreme and fluctuating bottom pressure characteristics at the stilling basin entrance area. With increasing chute slope, the latter were found to significantly magnify. However, such increased magnitudes were not expected to provoke cavitation damage as stepped chute inflows induced bottom aeration at the basin entrance, irrespective of the chute slope.
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Gama, Italon Rilson Vicente, André Luiz Andrade Simões, Harry Edmar Schulz i Rodrigo De Melo Porto. "CÓDIGO LIVRE PARA SOLUÇÃO NUMÉRICA DAS EQUAÇÕES DE SAINT-VENANT EM CANAIS TRAPEZOIDAIS ASSIMÉTRICOS". Revista Eletrônica de Gestão e Tecnologias Ambientais 8, nr 2 (24.12.2020): 145. http://dx.doi.org/10.9771/gesta.v8i2.38913.
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<p>Ondas de cheia em canais e ondas produzidas por manobras em comportas são alguns fenômenos simulados com as equações de Saint-Venant em aplicações de engenharia. Um novo código foi desenvolvido para a solução dessas equações aplicadas a um canal trapezoidal assimétrico, empregando o método de volumes finitos de Lax e Friedrichs. Foi adotada uma linguagem de programação reconhecida por um <em>software</em> livre. Três testes numéricos foram realizados. O primeiro, correspondente à passagem de uma onda de cheia em um canal retangular, apresentou aderência aos resultados obtidos com a solução calculada através do método implícito de Preissmann, com desvio relativo máximo de 1,4% para a velocidade e de 0,81% para a altura de escoamento. O segundo teste resolveu o escoamento em um canal de fundo variado que induz à formação de um ressalto hidráulico. As comparações dos presentes resultados com aqueles de simulações publicadas recentemente resultaram em um desvio máximo de 2,3% para as alturas de escoamento, a montante e a jusante do ressalto hidráulico. Para as posições médias do ressalto hidráulico, o desvio foi de 2,4%. Na terceira comparação, simulou-se um ressalto hidráulico em um canal trapezoidal assimétrico de forte declividade, tendo sido encontrada uma solução com desvios relativos menores que 1% para os escoamentos a montante e a jusante do ressalto, quando comparados aos resultados calculados com o método de MacCormack. A posição média do ressalto nesta terceira comparação apresentou um desvio de 5,5% em relação aos resultados anteriores. Os desvios calculados indicam que o código desenvolvido é capaz de resolver escoamentos variáveis em canais com e sem a formação de ressaltos hidráulicos. Este é um resultado de cunho prático, pois mostra que códigos livres podem ser usados na prática da hidráulica em geometrias não-convencionais.</p><p> </p><p align="center">OPEN SOURCE FOR NUMERICAL SOLUTION OF SAINT-VENAN EQUATIONS IN ASYMMETRIC TRAPEZOIDAL OPEN-CHANNELS</p><p>Flood waves in channels, positive waves produced when operating floodgates, and the hydraulic jump are some phenomena simulated with the Saint-Venant equations in practical engineering applications. A new code was developed to solve these equations applied to an asymmetric trapezoidal channel using the Lax-Friedrichs finite volumes method. A programming language recognized by a free software was used. Three numerical tests were performed. The first, corresponding to the passage of a flood wave in a rectangular channel, showed adherence to results of the solution calculated using the Preissmann implicit method, presenting a maximum relative deviation of 1.4% for the speed and 0.81% for the flow height. The second test solved the flow in a channel with a variable bed that induces the formation of a hydraulic jump. Comparisons of the present results with those of recently published simulations produced a maximum deviation of 2.3% for the flow heights, upstream and downstream of the hydraulic jump. For the mean positions of the hydraulic jump the deviation was 2.4%. In the third comparison a hydraulic jump was simulated in an asymmetric trapezoidal channel with a strong slope, obtaining a solution with relative deviations less than 1% for flows upstream downstream of the jump, when compared to the results calculated with the MacCormack method. The average position of the jump in this third comparison showed a deviation of 5.5% in relation to the former results. The calculated deviations indicate that the developed code is capable of solving variable flows in channels with and without the formation of hydraulic jumps. This is a practical result, because it shows that open codes can be used in the practice of hydraulics in nonconventional geometries.</p>
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Qi, Lan, Hui Chen, Xiao Wang, Wencai Fei i Donghai Liu. "Establishment and application of three-dimensional realistic river terrain in the numerical modeling of flow over spillways". Water Supply 18, nr 1 (31.05.2017): 119–29. http://dx.doi.org/10.2166/ws.2017.101.
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Abstract We present an integrated three-dimensional (3D) spillway model where the realistic and complicated river terrain is implemented by the platform CATIA (Computer Aided Three Dimensional Interactive Application). This integrated 3D spillway model allows for complicated topographic and geomorphic conditions and describes the spatial distribution of the spillway dam (upstream reservoir, downstream river channel and the spillway dam itself) precisely, thus making it a real alternative to the physical model. Furthermore, this model provides the premise and possibility of a full-scale simulation of the spillway flow, that is, it can not only be used to study the hydraulics on the spillway face, but also can be used to study the hydraulics along the downstream river channel and estimate the scour problem associated with both the spillway flow and downstream river channel. In this model, turbulence was simulated using RNG k−ɛ equations. The flow velocity and surface pressure from the numerical model were verified by the data from experiments. Moreover, the river flow was studied and flow velocities downstream were obtained. The scour formed downstream of a ski-jump was also studied in this study on the location and shape of a scour hole. In all, this study provides new approaches for solving relevant hydraulic engineering problems.
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Duguay, Jason M., i R. W. Jay Lacey. "Numerical study of an innovative fish ladder design for perched culverts". Canadian Journal of Civil Engineering 43, nr 2 (luty 2016): 173–81. http://dx.doi.org/10.1139/cjce-2014-0436.
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A fish ladder designed to facilitate fish passage at the outlet end of perched culverts is investigated with a 3D computational fluid dynamics model. The fish ladder consists of a series of alternating arch baffles with geometries providing options for fish passage over varying flow and debris conditions within the ladder. At high flows, the baffle’s protruding center arch increases pool depth, reducing the volumetric bulk turbulence of the pools and improving fish habitat. The arch baffle is compared to a standard baffle design currently in use and demonstrates potential advantages for fish passage. A recirculation zone of low velocity occupies a large volume of the pool believed to provide appropriate hydraulic habitat for resting and staging jump attempts upstream. This numerical study provides an acceptable design for future physical prototype testing in the laboratory or field to verify hydraulics and evaluate fish passage effectiveness.
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Zendrato, Nur Lely Hardianti, Asrini Chrysanti, Bagus Pramono Yakti, Mohammad Bagus Adityawan, Widyaningtias i Yadi Suryadi. "Application of Finite Difference Schemes to 1D St. Venant for Simulating Weir Overflow". MATEC Web of Conferences 147 (2018): 03011. http://dx.doi.org/10.1051/matecconf/201814703011.
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Depth averaged equations are commonly used for modelling hydraulics problems. Nevertheless, the model may not be able to accurately assess the flow in the case of different flow regimes, such as hydraulic jump. The model requires appropriate numerical method or other numerical treatments in order to simulate the case accurately. A finite volume scheme with shock capturing may provide a good result, but it is time consuming as compared to the commonly used finite difference schemes. In this study, 1D St. Venant equation is solved using Artificial Viscosity Lax-Wendroff and Mac-Cormack with TVD filter schemes to simulate an experiment case of weir overflow. The case is chosen to test each scheme ability in simulating flow under different flow regimes. The simulation results are benchmarked to the observed experimental data from previous study. Additionally, to observe the scheme efficiency, the simulation time between the models are compared. Therefore, the most accurate and efficient scheme can be determined.
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Xiao, Yexiang, Zhengwei Wang, Jidi Zeng, jintai Zheng, Jiayang Lin i Lanjin Zhang. "Prototype and numerical studies of interference characteristics of two ski-jump jets from opening spillway gates". Engineering Computations 32, nr 2 (20.04.2015): 289–307. http://dx.doi.org/10.1108/ec-04-2013-0104.
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Purpose – The purpose of this paper is to experimentally and numerically investigate the interference characteristics between two ski-jump jets on the flip bucket in a large dam spillway when two floodgates are running. Design/methodology/approach – The volume of fluid (VOF) method together with the Realizable k-ε turbulence model were used to predict the flow in two ski-jump jets and the free surface motion in a large dam spillway. The movements of the two gates were simulated using a dynamic mesh controlled by a User Defined Function (UDF). The simulations were run using the prototype dam as the field test to minimize errors due to scale effects. The simulation results are compared with field test observations. Findings – The transient flow calculations, accurately predict the two gate discharges compared to field data with the predicted ski-jump jet interference flow pattern similar to the observed shapes. The transient simulations indicate that the main reason for the deflected nappe is the larger opening difference between the two gates as the buttress side gate closes. When both gates are running, the two ski-jump jets interfere in the flip bucket and raise the jet nappe to near the buttress to form a secondary flow on this jet nappe surface. As the gate continues to close, the nappe surface continues to rise and the surface secondary flow become stronger, which deflects the nappe over the side buttress. Originality/value – A dynamic mesh is used to simulate the transient flow behavior of two prototype running gates. The transient flow simulation clarifies the hydraulics mechanism for how the two ski-jump jets interfere and deflect the nappe.
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Khatsuria, R. M. "Discussion of “Ski Jump Hydraulics” by Valentin Heller, Willi H. Hager, and Hans-Erwin Minor". Journal of Hydraulic Engineering 132, nr 10 (październik 2006): 1115–16. http://dx.doi.org/10.1061/(asce)0733-9429(2006)132:10(1115).
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Novak, Pavel. "Discussion of “Ski Jump Hydraulics” by Valentin Heller, Willi H. Hager, and Hans-Erwin Minor". Journal of Hydraulic Engineering 132, nr 10 (październik 2006): 1116. http://dx.doi.org/10.1061/(asce)0733-9429(2006)132:10(1116).
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Heller, Valentin, Willi H. Hager i Hans-Erwin Minor. "Closure to “Ski Jump Hydraulics” by Valentin Heller, Willi H. Hager, and Hans-Erwin Minor". Journal of Hydraulic Engineering 132, nr 10 (październik 2006): 1117. http://dx.doi.org/10.1061/(asce)0733-9429(2006)132:10(1117).
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Kouba, G. E., i W. P. Jepson. "The Flow of Slugs in Horizontal, Two-Phase Pipelines". Journal of Energy Resources Technology 112, nr 1 (1.03.1990): 20–24. http://dx.doi.org/10.1115/1.2905707.
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The flow characteristics in horizontal slug flow are studied experimentally in the Harwell Laboratory 150-mm-dia pipeline. If a frame of reference is taken as moving with the translational velocity of the slug, measurements of the Froude number in the liquid film ahead of the slug were always greater than unity while the Froude number within the slug was in general less than unity. This illustrates a change in flow from super to subcritical flow and the presence of a hydraulic jump. Different types of flow are noticed using high-speed video equipment and these types closely resemble those reported by open-channel hydraulics tests. The distribution of gas in the slug body is only homogeneous at high-mixture velocities and the effect of buoyancy on the gas is more noticeable at low gas velocities. The liquid fraction in the slug is shown to be directly dependent on the Froude number in the liquid film. The ratio of the translational velocity of the slug to the mixture velocity decreases continuously from 2.0 at low-mixture velocities to 1.25 and a mixture velocity of approximately 3m/s. After this point, it remains constant at 1.25.
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Clarke, Garry K. C. "Hydraulics of subglacial outburst floods: new insights from the Spring–Hutter formulation". Journal of Glaciology 49, nr 165 (2003): 299–313. http://dx.doi.org/10.3189/172756503781830728.
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AbstractUsing a slightly modified form of the Spring–Hutter equations, glacial outburst floods are simulated from three classic sites, “Hazard Lake”, Yukon, Canada, Summit Lake, British Columbia, Canada, and Grímsvötn, Iceland, in order to calibrate the hydraulic roughness associated with subglacial conduits. Previous work has suggested that the Manning roughness of the conduits is remarkably high, but the new calibration yields substantially lower values that are representative of those for natural streams and rivers. The discrepancy can be traced to a poor assumption about the effectiveness of heat transfer at the conduit walls. The simulations reveal behaviour that cannot be inferred from simplified theories: (1) During flood onset, water pressure over much of the conduit can exceed the confining pressure of surrounding ice. (2) Local values of fluid potential gradient can differ substantially from the value averaged over the length of the conduit, contradicting an assumption of simple theories. (3) As the flood progresses, the location of flow constrictions that effectively control the flood magnitude can jump rapidly over large distances. (4) Predicted water temperature at the conduit outlet exceeds that suggested by measurements of exit water temperature.
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Borroni, Massimiliano, i Vladimiro Boselli. "HYDRAULICS AND HYDROLOGY IN A PASSAGE OF THE KITĀB AL-ĀṮĀR AL-BĀQIYA BY AL-BĪRŪNĪ". Arabic Sciences and Philosophy 31, nr 2 (23.08.2021): 159–82. http://dx.doi.org/10.1017/s0957423921000059.
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AbstractThe authors translate and comment a digression from the Kitāb al-āṯār al-bāqiya on several hydraulic and hydrological subjects. The passage reveals al-Bīrūnī’s understanding of fluvial regimes, water physical behaviour, and of a handful of peculiar natural phenomena. Al-Bīrūnī departs from a discussion of weather forecast and seasonal fluvial regimes of the Tigris, Euphrates, Oxus, and Nile. The main concern of al-Bīrūnī is to defend the principle that water moves only downwards in absence of external forces. In doing so, the Khwarazmian scientist touches on the origin of salinity of the seas, the functioning of syphons related hydraulic machines, and relates a report of an artificial phenomenon, that he dismisses as result of faulty observations, that could be recognised as a hydraulic jump. In addition, the passage contains much relevant information on al-Bīrūnī’s understanding of the inhabitability of subequatorial regions, the possibility of the void, and the water cycle.
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Castillo, C., R. Pérez i J. A. Gómez. "A conceptual model of check dam hydraulics for gully control". Hydrology and Earth System Sciences Discussions 10, nr 9 (30.09.2013): 11901–41. http://dx.doi.org/10.5194/hessd-10-11901-2013.
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Abstract. There is little information in scientific literature regarding the modifications induced by check dam systems in flow regimes in restored gully reaches, despite it being a crucial issue for the design of conservation measures. Here, we develop a conceptual model to classify flow regimes in straight rectangular channels for initial and dam-filling conditions as well as a method of estimating efficiency in order to provide guidelines for optimal design. The model integrates several previous mathematical approaches for assessing the main processes involved (hydraulic jump HJ, impact flow, gradually varied flows). Its performance was compared with the simulations obtained from IBER, a bi-dimensional hydrodynamic model. The impact of check dam spacing (defined by the geometric factor of influence c) on efficiency was explored. Eleven main classifications of flow regimes were identified depending on the element and level of influence. The model produced similar results when compared with IBER, but led to higher estimations of HJ and impact lengths. Total influence guaranteed maximum efficiency and HJ control defining the location of the optimal c. Geometric total influence (c = 1) was a valid criterion for the different stages of the structures in a wide range of situations provided that hydraulic roughness conditions remained high within the gully, e.g. through revegetation. Our total influence criterion involved shorter spacing than that habitually recommended in technical manuals for restoration, but was in line with those values found in spontaneous and stable step-pools systems, which might serve as a reference for man-made interventions.
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Haris, Abdul. "Potensi Penggunaan Lompatan Hidrolik Dari Beda Bukaan Gate Pada Gate Valve Untuk Proses Koagulasi". Jurnal Skala Kesehatan 13, nr 1 (2.02.2022): 27–36. http://dx.doi.org/10.31964/jsk.v13i1.339.
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Mixing coagulant and water can take advantage of the turbulence that occurs when a hydraulic jump occurs in a channel. The hydraulic jump occurs due to the difference in slope of the two segments in a channel. In a hydraulic jump (water jump), the flow velocity decreases suddenly from V1 to V2. Correspondingly, the flow depth also increases rapidly from y1 to y2 (Triatmodjo, 2003). The use of hydraulic jumps is relatively cheaper because it does not require a stirrer such as a motor or air pump.
The hydraulic jump used comes from the size of the gate valve opening at the outlet of the water reservoir. The research variation is a combination of gate valve openings (60o, 80o, 90o); coagulant injection point (X=before the jump, Y=when the jump, Z=after the jump); settling time (10, 20, 30 minutes).
The results showed that the efficiency of turbidity removal using hydraulic jumps as a coagulator of the water purification process with aluminum sulfide was 74.2% from the initial turbidity of 81.6 NTU to 19 – 23.3 NTU. The effectiveness of the use of hydraulic jumps on the use of the impeller method as a cogulator is 83%.
Keywords: hydraulic jump, gate valve opening
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Gregg, M. C., i L. J. Pratt. "Flow and Hydraulics near the Sill of Hood Canal, a Strongly Sheared, Continuously Stratified Fjord". Journal of Physical Oceanography 40, nr 5 (1.05.2010): 1087–105. http://dx.doi.org/10.1175/2010jpo4312.1.
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Abstract Hood Canal, a long fjord in Washington State, has strong tides but limited deep-water renewal landward of a complex constriction. Tide-resolving hydrographic and velocity observations at the constriction, with a depth-cycling towed body, varied markedly during three consecutive years, partly because of stratification variations. To determine whether hydraulic control is generally important and to interpret observations of lee waves, blocking, and other features, hydraulic criticality is estimated over full tidal cycles for channel wide internal wave modes 1, 2, and 3, at five cross-channel sections, using mode speeds from the extended Taylor–Goldstein equation. These modes were strongly supercritical during most of ebb and flood on the gentle seaward sill face and for part of flood at the base of the steep landward side. Examining local criticality along the thalweg found repeated changes between mode 1 being critical and supercritical approaching the sill crest during flood, unsurprising given local minima and maxima in the cross-sectional area, with the sill crest near a maximum. Density crossing the sill sometimes resembled an overflow with an internal hydraulic control at the sill, followed by a hydraulic jump or lee wave. Long-wave speeds, however, suggest cross waves, particularly along the shallower gentler side, where flow downstream of a large-amplitude wave was uniformly supercritical. Supercritical approaching the sill, peak ebb was critical to mode 1 and supercritical to modes 2 and 3 at the base while forming a sluggish dome of dense water over the sill. Full interpretation exceeds observations and existing theory.
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Fedorov, Alexey V., i W. Kendall Melville. "Hydraulic jumps at boundaries in rotating fluids". Journal of Fluid Mechanics 324 (10.10.1996): 55–82. http://dx.doi.org/10.1017/s0022112096007835.
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We consider three-dimensional hydraulic jumps (shocks) propagating along boundaries in rotating fluids. This study is motivated by earlier work (Fedorov & Melville 1995), which dealt with the evolution to breaking of nonlinear Kelvin waves. We obtain the jump relations and derive an evolution equation for the jump as it propagates along the boundary. It is shown that after some initial adjustment the Kelvin-type jump assumes a permanent form and propagates with a constant velocity along the boundary or the coast. At some distance offshore the jump becomes oblique to the coastline, and the final shape of the jump and its speed depend only on the jump strength. The jump gives rise to a moderate mass transport offshore. The potential vorticity remains almost constant across the jump. The energy loss in the jump is proportional to the third power of the jump amplitude, which is similar to classical two-dimensional hydraulic jumps in non-rotating fluids. Jump properties are discussed for both weak and strong nonlinearity, and the role of a boundary layer region behind the leading edge of the jump is considered.
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THORPE, S. A., i I. KAVCIC. "The circular internal hydraulic jump". Journal of Fluid Mechanics 610 (8.08.2008): 99–129. http://dx.doi.org/10.1017/s0022112008002553.
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Circular hydraulic jumps are familiar in single layers. Here we report the discovery of similar jumps in two-layer flows. A thin jet of fluid impinging vertically onto a rigid horizontal plane surface submerged in a deep layer of less-dense miscible fluid spreads radially, and a near-circular internal jump forms within a few centimetres from the point of impact with the plane surface. A jump is similarly formed as a jet of relatively less-dense fluid rises to the surface of a deep layer of fluid, but it appears less stable or permanent in form. Several experiments are made to examine the case of a downward jet onto a horizontal plate, the base of a square or circular container. The inlet Reynolds numbers, Re, of the jet range from 112 to 1790. Initially jumps have an undular, laminar form with typically 2–4 stationary waves on the interface between the dense and less-dense layers but, as the depth of the dense layer beyond the jump increases, the transitions become more abrupt and turbulent, resulting in mixing between the two layers. During the transition to a turbulent regime, single and sometimes moving multiple cusps are observed around the periphery of jumps. A semi-empirical model is devised that relates the parameters of the laboratory experiment, i.e. flow rate, inlet nozzle radius, kinematic viscosity and reduced gravity, to the layer depth beyond the jump and the radius at which an undular jump occurs. The experiments imply that surface tension is not an essential ingredient in the formation of circular hydraulic jumps and demonstrate that stationary jumps can exist in stratified shear flows which can be represented as two discrete layers. No stationary circular undular jumps are found, however, in the case of a downward jet of dense fluid when the overlying, less-dense, fluid is stratified, but a stationary turbulent transition is observed. This has implications for the existence of stationary jumps in continuously stratified geophysical flows: results based on two-layer models may be misleading. It is shown that the Froude number at which a transition of finite width occurs in a radially diverging flow may be less than unity.
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Baines, Peter G. "Internal hydraulic jumps in two-layer systems". Journal of Fluid Mechanics 787 (7.12.2015): 1–15. http://dx.doi.org/10.1017/jfm.2015.662.
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This paper describes a new model of internal hydraulic jumps in two-layer systems that places no restrictions (such as the Boussinesq approximation) on the densities of the two fluids. The model is based on that of Borden and Meiburg (J. Fluid Mech., vol. 276, 2013, R1) for Boussinesq jumps, and has the appropriate behaviour in various limits (single-layer, small amplitude, Boussinesq, infinite depth). The energy flux loss in each layer across the jump is positive for all realistic jumps, reaching a maximum for the jump with maximum speed. Larger-amplitude jumps are possible, with decreasing energy loss, down to the ‘conjugate state’ of zero energy loss. However, it is argued that such states may be difficult to realise in practice, and if formed, will tend to the jump with maximum speed. The energy loss is mostly in the contracting layer unless the density there is small. The two-layer model is extended to incorporate mixing between the layers within the jump, with mixing based on the Richardson number.
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Nettleton, Peter C., i John A. McCorquodale. "Radial flow stilling basins with baffle blocks". Canadian Journal of Civil Engineering 16, nr 4 (1.08.1989): 489–97. http://dx.doi.org/10.1139/l89-079.
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A total of 120 tests of forced radial flow hydraulic jumps have been analyzed in order to develop curves and equations for the design of radial stilling basins. The jump depth, the water surface profile, wave amplitudes, the allowable flare angle, and the jump length are defined in terms of entrance conditions, the baffle position, and the baffle height. An example design is given and compared with a USBR (U.S. Bureau of Reclamation) Type III stilling basin. Key words: forced hydraulic jump, radial flow, design, stilling basins, baffles, radial hydraulic jump, circular hydraulic jump.
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BOUDET, J. F., Y. AMAROUCHENE, B. BONNIER i H. KELLAY. "The granular jump". Journal of Fluid Mechanics 572 (23.01.2007): 413–31. http://dx.doi.org/10.1017/s002211200600365x.
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When a fluid jet hits a solid surface, a hydraulic jumps occurs. This jump sharply delimits a thin film of liquid from a thicker film. We show here that a granular jet impinging on a solid surface also gives rise to several features reminiscent of the hydraulic jump and we refer to this situation as the granular jump. We describe, in detail, this phenomenon and show that if many of its features can be understood in analogy with the hydraulic jump, others are directly related to the granular nature of the medium and, in particular, the small-scale dynamics of the jump.
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Teymourtash, A. R., i M. Mokhlesi. "Experimental investigation of stationary and rotational structures in non-circular hydraulic jumps". Journal of Fluid Mechanics 762 (3.12.2014): 344–60. http://dx.doi.org/10.1017/jfm.2014.646.
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AbstractWhen a vertical liquid jet impacts on a solid horizontal surface, the first expectation is to have a circular hydraulic jump. However, in some conditions, for highly viscous fluids, the transition from supercritical to subcritical flow occurs with non-circular shapes such as polygons. Indeed, a quick rotational wave appears on the circular jump before the formation of a polygonal form, which may be related to the Rayleigh–Plateau instability. In this paper, stable polygonal jumps are studied to complete this research. The region of stability is defined for polygonal jumps, and the dependence of this region on the flow governing dimensionless groups is determined experimentally. The results confirm the multistability (hysteresis) of the polygonal jumps, and imply that polygonal jumps with different corner numbers can be created in a certain parameter regime. The size and curvature of the sides of the polygons due to variations of flow rate and downstream obstacle height are also investigated. In addition to the stable ones, our experiments reveal a new type of polygonal jump that has an unstable structure and displays a rotational behaviour with a constant angular velocity, which we call it, ‘rotational hydraulic jump’. It is observed that the angular velocity of this kind of jump depends on the jet flow rate, jet radius and downstream height of the jump. Our observations suggest that the nature of the rotational jump is some kind of surface wave along the jump in clockwise or anticlockwise direction. It seems that the rotational jump has a flow structure that is the same as a type IIb jump. The jump dimensions are studied; the inscribed and circumscribed circular radii of each polygon are measured in order to compare the various polygons together and to find a mean jump radius to compare with Watson’s theory.
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Alghwail, Amad Deen Abdusalam. "Investigation of the Perfect Hydraulic Jump in Horizontal Rectangular Channel". مجلة الجامعة الأسمرية: العلوم التطبيقية 6, nr 5 (31.12.2021): 222–29. http://dx.doi.org/10.59743/aujas.v6i5.1144.
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Accelerating the process of transition from supercritical to subcritical flow, by formation a forced hydraulic jump at the contract section (Forced perfect hydraulic jump), is one of the most important measures, in decreasing flow velocity, water energy dissipation and alleviation the scouring problem, leading to lessening the required protection length against the erosion issues in the bed of downstream of the channel. In the current study, physical model was prepared precisely at fluid mechanics laboratory in the faculty of Engineering/Alkhums at Elmergib University. Comprehensive experiments were conducted to evaluate measured and calculated characteristics of the perfect free jump, and consequently, the existence of the perfect hydraulic jump is investigated. Eventually, equation was derived that might be used to guarantee the existence of a free perfect jump, which is the limiting condition between both repelled and drowned jumps as well as, the limiting condition between both repelled and drowned jumps was graphically found.
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Houichi, Larbi, Noureddine Dechemi, Salim Heddam i Bachir Achour. "An evaluation of ANN methods for estimating the lengths of hydraulic jumps in U-shaped channel". Journal of Hydroinformatics 15, nr 1 (21.09.2012): 147–54. http://dx.doi.org/10.2166/hydro.2012.138.
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Modelling of hydraulic characteristics of jump using theoretical and empirical models has always been a difficult task. The length of jump may be defined as the distance measured from the toe of the jump to the location of the surface rise. Due to high turbulence this length cannot be determined easily by theory. However, it has been investigated experimentally so as to design the stilling basins with hydraulic jumps. In this work, the control of a hydraulic jump by broad-crested sills in a U-shaped channel is recalled theoretically and experimentally examined. The study begins with a multiple regression (MR) analysis. Then, and in order to model the relative lengths of hydraulic jumps, we have implemented and evaluated two different artificial neural networks (ANN): multilayer perceptron neural network (MLPNN) and generalized regression neural network (GRNN). The results demonstrate the predictive strength of GRNN and its potential to predict hydraulic problems with an adaptive spread value. However, the MLPNN model remains best classified by these indexes of performance.
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Baddour, R. E. "Thermal hydraulic jump: theory and experiment". Journal of Fluid Mechanics 226 (maj 1991): 243–56. http://dx.doi.org/10.1017/s0022112091002379.
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A thermally stratified internal hydraulic jump in a fresh water ambient, which has a temperature equal to or greater than 4 °C, is investigated theoretically and experimentally. The thermal jump solutions obtained using a nonlinear buoyancy function are compared with the density jump solutions obtained using a linear buoyancy function. The study reveals considerable difference between thermal and density jump behaviour in a range of temperature above 4 °C. The error of treating a thermal jump as a density jump is found to increase with Froude number and temperature difference and decrease with ambient temperature. Thermal jump-experiments are conducted at ambient water temperatures of 4 °C and 16 °C. The two sets of experiments have identical Froude number, Reynolds number and temperature difference. Experimental observations compare favourably with the thermal jump theory. The analysis of temperature fluctuations suggests that ambient temperature is also modifying the internal mixing characteristics of thermal jumps.
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Singh, Digvijay, i Arup Kumar Das. "Computational simulation of radially asymmetric hydraulic jumps and jump–jump interactions". Computers & Fluids 170 (lipiec 2018): 1–12. http://dx.doi.org/10.1016/j.compfluid.2018.04.024.
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Gou, Wenjuan, Huiping Li, Yunyi Du, Hongxia Yin, Fang Liu i Jijian Lian. "Effect of Sediment Concentration on Hydraulic Characteristics of Energy Dissipation in a Falling Turbulent Jet". Applied Sciences 8, nr 9 (15.09.2018): 1672. http://dx.doi.org/10.3390/app8091672.
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The effect of sediment on the hydraulics of jet energy dissipation is an urgent issue for high dams built on sediment-laden rivers. Accordingly, flume experiments were conducted using a ski-jump type energy dissipator in flows of four sediment concentrations (0 kg/m3, 50 kg/m3, 150 kg/m3, and 250 kg/m3) to determine the effects on discharge, flow regime, and hydrodynamic pressure in a plunge pool. The results demonstrate that the effect of sediment on discharge is constant, regardless of sediment concentration, when compared to fresh water. The width of the nappe decreased with increasing concentrations of sediment. The length of the jet trajectory increased with upstream water head. The time-averaged pressure and fluctuation pressure both exhibited peaks, describing the impact of the jet on the bottom of the plunge pool. The maximum time-averaged pressure and maximum fluctuating pressure both noticeably increased with upstream water head and slightly increased with sediment concentration for a given flow condition. The results also demonstrated that the dominant frequency of fluctuation trends to lower values, and that both the fluctuating energy and vortex scale increase with increasing sediment concentrations due to increased viscosity. These findings can be used to improve energy dissipation in dams on sediment-laden rivers.
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Mejean, Ségolène, Thierry Faug i Itai Einav. "A general relation for standing normal jumps in both hydraulic and dry granular flows". Journal of Fluid Mechanics 816 (6.03.2017): 331–51. http://dx.doi.org/10.1017/jfm.2017.82.
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Steady free-surface flows can produce sudden changes in height and velocity, namely standing jumps, which demarcate supercritical from subcritical flows. Standing jumps have traditionally been observed and studied experimentally with water in order to mimic various hydraulic configurations, for instance in the vicinity of energy dissipators. More recently, some studies have emerged that investigate standing jumps formed in flows of dry granular materials, which are relevant to the design of protection dams against avalanches. In the present paper, we present a new explicit relation for the prediction of the height of standing jumps. We demonstrate the robustness of the new relation proposed by revisiting and cross-comparing a great number of data sets on standing jumps formed in water flows on horizontal and inclined smooth beds, in water flows on horizontal rough beds, and in flows of dry granular materials down smooth inclines. Our study reveals the limits of the traditional one-to-one relation between the sequent depth ratio of the jump and the Froude number of the incoming supercritical flow, namely the Bélanger equation. The latter is a Rankine–Hugoniot relation which does not take into account the gravitational and frictional forces acting within the jump volume, over the jump length, as well as the possible density change across the jump when the incoming fluid is compressible. The newly proposed relation, which is exact for grains and a reasonable approximation for water, can solve all of these issues. However, this relation can predict the height of the standing jump only if another length scale, namely the length of the jump, is known. We conclude our study by discussing empirical but simple closure relations to get a reasonable estimate of the jump length for water flows and dry granular flows. These closure relations can be used to feed the general jump relation and then predict with accuracy the heights of the jumps in a number of situations, provided that well-calibrated friction laws – described in the present study – are considered.
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Castillo, C., R. Pérez i J. A. Gómez. "A conceptual model of check dam hydraulics for gully control: efficiency, optimal spacing and relation with step-pools". Hydrology and Earth System Sciences 18, nr 5 (12.05.2014): 1705–21. http://dx.doi.org/10.5194/hess-18-1705-2014.
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Abstract. There is little information in scientific literature regarding the modifications induced by check dam systems in flow regimes within restored gully reaches, despite it being a crucial issue for the design of gully restoration measures. Here, we develop a conceptual model to classify flow regimes in straight rectangular channels for initial and dam-filling conditions as well as a method of estimating efficiency in order to provide design guidelines. The model integrates several previous mathematical approaches for assessing the main processes involved (hydraulic jump, impact flow, gradually varied flows). Ten main classifications of flow regimes were identified, producing similar results when compared with the IBER model. An interval for optimal energy dissipation (ODI) was observed when the steepness factor c was plotted against the design number (DN, ratio between the height and the product of slope and critical depth). The ODI was characterized by maximum energy dissipation and total influence conditions. Our findings support the hypothesis of a maximum flow resistance principle valid for a range of spacing rather than for a unique configuration. A value of c = 1 and DN ~ 100 was found to economically meet the ODI conditions throughout the different sedimentation stages of the structure. When our model was applied using the same parameters to the range typical of step-pool systems, the predicted results fell within a similar region to that observed in field experiments. The conceptual model helps to explain the spacing frequency distribution as well as the often-cited trend to lower c for increasing slopes in step-pool systems. This reinforces the hypothesis of a close link between stable configurations of step-pool units and man-made interventions through check dams.
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HOLLAND, DAVID M., RODOLFO R. ROSALES, DAN STEFANICA i ESTEBAN G. TABAK. "Internal hydraulic jumps and mixing in two-layer flows". Journal of Fluid Mechanics 470 (31.10.2002): 63–83. http://dx.doi.org/10.1017/s002211200200188x.
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Internal hydraulic jumps in two-layer flows are studied, with particular emphasis on their role in entrainment and mixing. For highly entraining internal jumps, a new closure is proposed for the jump conditions. The closure is based on two main assumptions: (i) most of the energy dissipated at the jump goes into turbulence, and (ii) the amount of turbulent energy that a stably stratified flow may contain without immediately mixing further is bounded by a measure of the stratification. As a consequence of this closure, surprising bounds emerge, for example on the amount of entrainment that may take place at the location of the jump. These bounds are probably almost achieved by highly entraining internal jumps, such as those likely to develop in dense oceanic over flows. The values obtained here are in good agreement with the existing observations of the spatial development of oceanic downslope currents, which play a crucial role in the formation of abyssal and intermediate waters in the global ocean.
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KATE, R. P., P. K. DAS i SUMAN CHAKRABORTY. "Hydraulic jumps due to oblique impingement of circular liquid jets on a flat horizontal surface". Journal of Fluid Mechanics 573 (luty 2007): 247–63. http://dx.doi.org/10.1017/s0022112006003818.
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An obliquely inclined circular water jet, impinging on a flat horizontal surface, confers a series of hydraulic jump profiles, pertaining to different jet inclinations and jet velocities. These jump profiles are non-circular, and can be broadly grouped into two categories, based on the angle of jet inclination, φ, made with horizontal. Jumps corrosponding to the range (25° < φ≤ 90°) are observed to be bounded by smooth curves, whereas those corresponding to φ≤ 25° are characterized by distinct corners. The present work attempts to find a geometric and hydrodynamic characterization of the spatial patterns formed as a consequence of such non-circular hydraulic jump profiles. Flow-visualization experiments are conducted to depict the shape of demarcating boundaries between supercritical and subcritical flows, and the corresponding radial jump locations are obtained. Theoretical calculations are also executed to obtain the radial locations of the jumps with geometrically smooth profiles. Comparisons are subsequently made between the theoretical predictions and the experimental observations, and a good agreement between these two can be observed. Jumps with corners, however, turn out to be comprised of strikingly contrasting profiles, which can be attributed to the ‘jump–jet’ interaction and the ‘jump-jump’ interaction mechanisms. A phenomenological explanation is also provided, by drawing an analogy from the theory of shock-wave interactions.
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Thorpe, S. A., J. Malarkey, G. Voet, M. H. Alford, J. B. Girton i G. S. Carter. "Application of a model of internal hydraulic jumps". Journal of Fluid Mechanics 834 (17.11.2017): 125–48. http://dx.doi.org/10.1017/jfm.2017.646.
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A model devised by Thorpe & Li (J. Fluid Mech., vol. 758, 2014, pp. 94–120) that predicts the conditions in which stationary turbulent hydraulic jumps can occur in the flow of a continuously stratified layer over a horizontal rigid bottom is applied to, and its results compared with, observations made at several locations in the ocean. The model identifies two positions in the Samoan Passage at which hydraulic jumps should occur and where changes in the structure of the flow are indeed observed. The model predicts the amplitude of changes and the observed mode 2 form of the transitions. The predicted dissipation of turbulent kinetic energy is also consistent with observations. One location provides a particularly well-defined example of a persistent hydraulic jump. It takes the form of a 390 m thick and 3.7 km long mixing layer with frequent density inversions separated from the seabed by some 200 m of relatively rapidly moving dense water, thus revealing the previously unknown structure of an internal hydraulic jump in the deep ocean. Predictions in the Red Sea Outflow in the Gulf of Aden are relatively uncertain. Available data, and the model predictions, do not provide strong support for the existence of hydraulic jumps. In the Mediterranean Outflow, however, both model and data indicate the presence of a hydraulic jump.
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Thorpe, S. A., i Lin Li. "Turbulent hydraulic jumps in a stratified shear flow. Part 2". Journal of Fluid Mechanics 758 (7.10.2014): 94–120. http://dx.doi.org/10.1017/jfm.2014.502.
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AbstractConditions are found in which stationary turbulent hydraulic jumps can occur in a shallow stably stratified shear flow of depth $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}h_{1}$ moving over a rigid horizontal boundary at $z =0$ and below a deep static layer of uniform density. The flow approaching a jump has uniform density and speed to a height $z = h_{1}\eta _{1}\ (\eta _{1} \le 1)$. Above this, in an interfacial layer $h_{1}\eta _{1}<z<h_{1}$, the density and speed decrease linearly to their values in a deep uniform and static layer above $z = h_{1}$. The flow downstream of a jump is supposed to be similarly stratified to a height $ h_{2}$, but with a lower layer of height $h_{2}\eta _{2}$. The flow approaching the jump is specified by $\eta _{1}$ and by a Froude number, Fr. Stationary jumps occur in the flow only if Fr is large enough to ensure that no internal waves can propagate upstream from the transition region. The flow downstream of the jump satisfies conditions of conservation of mass, volume and momentum fluxes, and closure is obtained by the selection of its gradient Richardson number, ${\mathit{Ri}}_{F}$. It is necessary that $\eta _{1} \ge \eta _{2}$ for the entrainment of fluid into the moving layer from the overlying deep layer to be non-negative. The jump height, $q = h_{2}/h_{1}$, always exceeds unity (i.e. jumps are, overall, of elevation) and the mean thickness of the flowing layer, $h_{i}(1+ \eta _{i})/2\ (i = 1, 2)$, increases through the jump. There are two types of jumps, one in which the thickness of the lower layer, $h_{i}\eta _{i}$, increases (and all isopycnals are raised by the transition) and a second in which $h_{i}\eta _{i}$ decreases even though $q$ and the mean thickness ratio, $h_{2}(1+ \eta _{2})/ h_{1}(1 + \eta _{1})$, are greater than one. Two possible solutions for the downstream flow (i.e. two jumps of different heights, $q$, and different shape parameters, $\eta _{2}$) are possible in limited ranges of Fr depending on $\eta _{1}$ when $\eta _{1} > \eta _{2}$, $= \eta _{2max}$, where $\eta _{2max} =0.744$ when ${\mathit{Ri}}_{F} = 1/3$. Only single solutions are possible for upstream flows with $\eta _{1}< \eta _{2max}$. The two branches of the double solutions are distinguishable. For the ‘upper’ solutions, $\eta _{2}$ increases as Fr increases, and all isopycnals are raised in the jump. The ‘lower’ of the double solutions are continuous with the single solutions (with $\eta _{1}<\eta _{2max}$), $\eta _{2}$ decreases as Fr increases, and for most of the jumps the lower uniform layer decreases in thickness through the jump. For all solutions there is a reduction in the energy flux as fluid passes through a transition, and hence a loss of energy in the turbulent mixing of a jump, as required on physical grounds. The Osborn efficiency factor, $\varGamma $, is generally less than the canonical value of 0.2 for upper branch solutions but greater than 0.2 for the single and lower branch solutions. A loss in vorticity flux occurs in a turbulent jump. For a hydraulic jump to be possible when $\eta _{2}$ is less than approximately 0.3, it is not generally necessary that the flow approaching a jump is unstable to Kelvin–Helmholtz (K–H) instability, but it is more common that upstream flows in which jumps can occur are dynamically unstable.
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Safronov, A. A., A. A. Koroteev, N. I. Filatov i N. A. Safronova. "Capillary Hydraulic Jump in a Viscous Jet". Nelineinaya Dinamika 15, nr 3 (2019): 221–31. http://dx.doi.org/10.20537/nd190302.
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Fatimah, Eldina, Azmeri Azmeri, Qurratul 'Aini, Muhammad Fauzi i Maimun Rizalihadi. "Analysis of the Hydraulic Jump Characteristics in a Stilling Basin to Avoid Dam Failure". International Journal of Disaster Management 6, nr 1 (2.06.2023): 75–88. http://dx.doi.org/10.24815/ijdm.v6i1.31990.
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Flooding may occur due to dam failure at downstream of the spillway. Stilling basin of the spillway plays an important role in reducing turbulence generated by hydraulic jumps. It can avoid flooding and local scouring as well. Therefore, this study aims to analyze hydraulic jump characteristics experimentally. Two series of structures namely initial (S0) and final (S1) were tested. The S0 model is the United States Bureau of Reclamation (USBR) III type, while S1 is set the adverse slope of 1:2 at the downstream and lowering the bottom elevation of the channel by 4 m. Measurements were taken on the length of hydraulic jumps, water level and high speed before-after hydraulic jumps at various return periods discharges (Q) of 2, 5, 10, 25, 50, 100 and 1000 years. It is found that at S1, the jump is submerged, causing the relative hydraulic jump height (y2-y1)/y1 to be 40-90% higher than S0. Furthermore, the compression of more than 50% of the hydraulic jump length ratio (Lj/y2) was indicated at S1. In addition, the energy dissipation efficiency (εt) obtained for each discharge at S1 ranged from 58-84% (good absorption). On the other hand, at S0, the εt produced was around 70-89% (Q2-Q50) and 45% (Q100 and Q1000). It can be concluded that the modification of USBR III can reduce the vulnerability of the bottom and downstream parts of the stilling basin. It is expected that the potential flood disaster due to the stilling basin failure of the dam can be eliminated. These results may be used as recommendation to the disaster management strategies, such as improving dam safety guidelines, informing emergency response plans, or guiding infrastructure design to withstand hydraulic forces.
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Honegger, David A., Merrick C. Haller, W. Rockwell Geyer i Gordon Farquharson. "Oblique Internal Hydraulic Jumps at a Stratified Estuary Mouth". Journal of Physical Oceanography 47, nr 1 (styczeń 2017): 85–100. http://dx.doi.org/10.1175/jpo-d-15-0234.1.
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AbstractObservations and analyses of two tidally recurring, oblique, internal hydraulic jumps at a stratified estuary mouth (Columbia River, Oregon/Washington) are presented. These hydraulic features have not previously been studied due to the challenges of both horizontally resolving the sharp gradients and temporally resolving their evolution in numerical models and traditional observation platforms. The jumps, both of which recurred during ebb, formed adjacent to two engineered lateral channel constrictions and were identified in marine radar image time series. Jump occurrence was corroborated by (i) a collocated sharp gradient in the surface currents measured via airborne along-track interferometric synthetic aperture radar and (ii) the transition from supercritical to subcritical flow in the cross-jump direction via shipborne velocity and density measurements. Using a two-layer approximation, observed jump angles at both lateral constrictions are shown to lie within the theoretical bounds given by the critical internal long-wave (Froude) angle and the arrested maximum-amplitude internal bore angle, respectively. Also, intratidal and intertidal variability of the jump angles are shown to be consistent with that expected from the two-layer model, applied to varying stratification and current speed over a range of tidal and river discharge conditions. Intratidal variability of the upchannel jump angle is similar under all observed conditions, whereas the downchannel jump angle shows an additional association with stratification and ebb velocity during the low discharge periods. The observations additionally indicate that the upchannel jump achieves a stable position that is collocated with a similarly oblique bathymetric slope.
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Welahettige, Prasanna, Bernt Lie i Knut Vaagsaether. "Flow regime changes at hydraulic jumps in an open Venturi channel for Newtonian fluid". Journal of Computational Multiphase Flows 9, nr 4 (31.07.2017): 169–79. http://dx.doi.org/10.1177/1757482x17722890.
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The aim of this paper is to study flow regime changes of Newtonian fluid flow in an open Venturi channel. The simulations are based on the volume of fluid method with interface tracking. ANSYS Fluent 16.2 (commercial code) is used as the simulation tool. The simulation results are validated with experimental results. The experiments were conducted in an open Venturi channel with water at atmospheric condition. The inlet water flow rate was 400 kg/min. The flow depth was measured by using ultrasonic level sensors. Both experiment and simulation were done for the channel inclination angles 0°, −0.7°, and −1.5°. The agreement between computed and experimental results is satisfactory. At horizontal condition, flow in the channel is supercritical until contraction and subcritical after the contraction. There is a hydraulic jump separating the supercritical and subcritical flow. The position of the hydraulic jump oscillates within a region of about 100 mm. Hydraulic jumps coming from the contraction walls to the upstream flow are the main reasons for the conversion of supercritical flow into subcritical flow. An “oblique jump” can be seen where there is a supercritical flow in the contraction. There is a triple point in this oblique jump: the triple point consists of two hydraulic jumps coming from the contraction walls and the resultant wave. The highest flow depth and the lowest velocity in the triple point are found at the oblique jump.
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Zare, H. K., i R. E. Baddour. "Three-dimensional study of spatial submerged hydraulic jump". Canadian Journal of Civil Engineering 34, nr 9 (1.09.2007): 1140–48. http://dx.doi.org/10.1139/l07-041.
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A three-dimensional (3D) study of spatial submerged hydraulic jumps (SSHJs) was carried out using a physical model for Froude numbers Fr1 = 2.00 and 3.75 and width ratios α = 0.20 and 0.33. Three orthogonal components of the velocity field were obtained with an acoustic Doppler velocimeter (ADV). The 3D velocity field has indicated that the jump consisted of a central jet-like flow, close to the channel bottom, surrounded by vertical and horizontal circulations (rollers). The circulation was predominantly in vertical planes in the channel central region of the flow and in horizontal planes close to the walls. Vertical and horizontal profiles of stream-wise velocity characterized the 3D roller with two length scales, Lrv and Lrh. The strength of the roller was stronger close to the walls than at the centreline of the jump. Sequent depth and energy head loss for submerged symmetric hydraulic jumps are discussed in terms of the submergence ratio S = y3/y2.Key words: hydraulic jump, spatial, submerged, roller length, sequent depth, energy dissipation.
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Ravi, M. R., R. A. W. M. Henkes i C. J. Hoogendoorn. "On the high-Rayleigh-number structure of steady laminar natural-convection flow in a square enclosure". Journal of Fluid Mechanics 262 (3.10.1994): 325–51. http://dx.doi.org/10.1017/s0022112094000522.
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Natural-convection flow in an enclosure with adiabatic horizontal walls and isothermal vertical walls maintained at a fixed temperature difference has been investigated. At high values of the natural-convection parameter, the Rayleigh number, a recirculating pocket appears near the corners downstream of the vertical walls, and the flow separates and reattaches at the horizontal walls in the vicinity of this recirculation. There is also a considerable thickening of the horizontal layer. In some previous studies by different authors, this corner flow was considered to be caused by an internal hydraulic jump, and the jump theory was used to predict bifurcation of the steady flow into periodic flow. The present work examines the corner phenomenon closely to decide if it is indeed caused by a hydraulic jump. The results of the analysis reveal the oversimplification of the problem made in the previous studies: there is no connection of the corner phenomenon with a hydraulic jump. The separation of flow at the ceiling is not a feature of hydraulic jumps, and the essential energy loss associated with hydraulic jumps is not observed in the corner flow. It is shown that the corner structure is caused by thermal effects. Owing to the temperature undershoots in vertical boundary layer, which are known to be caused by the stable thermal stratification of the core, relatively cold fluid reaches the upper corner. This cold fluid detaches from the ceiling like a plume at high Rayleigh numbers, and causes the separation and recirculation.
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Beirami, M. K., i M. R. Chamani. "Hydraulic jump in sloping channels: roller length and energy loss". Canadian Journal of Civil Engineering 37, nr 4 (kwiecień 2010): 535–43. http://dx.doi.org/10.1139/l09-175.
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This paper deals with the roller length and energy loss of a large variety of hydraulic jumps in horizontal and sloping channels. The supercritical upstream flow originated from a standard ogee weir. A stilling basin with bottom slopes of 0.0, −0.025, −0.050, −0.075, and −0.100 was used to generate the jumps. Based on the energy principle, a semi-empirical method to predict the roller length is presented. Predictions based on the proposed method agree well with the results reported by the authors and other researchers. It is shown that the energy loss in the classical jump is greater than that in any jump forming on negative or positive slopes.
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Rotunno, Richard, i George H. Bryan. "Numerical Simulations of Two-Layer Flow past Topography. Part II: Lee Vortices". Journal of the Atmospheric Sciences 77, nr 3 (26.02.2020): 965–80. http://dx.doi.org/10.1175/jas-d-19-0142.1.
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Abstract This study considers a two-layer fluid with constant density in each layer connected by a layer of continuously varying density for flows past topography in which hydraulic jumps with lee vortices are expected based on shallow-water theory. Numerical integrations of the Navier–Stokes equations at a Reynolds number high enough for a direct numerical simulation of turbulent flow allow an examination of the internal mechanics of the turbulent leeside hydraulic jump and how this mechanics is related to lee vortices. Analysis of the statistically steady state shows that the original source of lee-vortex vertical vorticity is through the leeside descent of baroclinically produced spanwise vorticity associated with the hydraulic jump. This spanwise vorticity is tilted to the vertical at the spanwise extremities of the leeside hydraulic jump. Turbulent energy dissipation in flow through the hydraulic jump allows this leeside vertical vorticity to diffuse and extend downstream. The present simulations also suggest a geometrical interpretation of lee-vortex potential-vorticity creation, a concept central to interpretations of lee vortices based on the shallow-water equations.
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Macián-Pérez, Juan, Francisco Vallés-Morán, Santiago Sánchez-Gómez, Marco De-Rossi-Estrada i Rafael García-Bartual. "Experimental Characterization of the Hydraulic Jump Profile and Velocity Distribution in a Stilling Basin Physical Model". Water 12, nr 6 (20.06.2020): 1758. http://dx.doi.org/10.3390/w12061758.
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The study of the hydraulic jump developed in stilling basins is complex to a high degree due to the intense velocity and pressure fluctuations and the significant air entrainment. It is this complexity, bound to the practical interest in stilling basins for energy dissipation purposes, which brings the importance of physical modeling into the spotlight. However, despite the importance of stilling basins in engineering, bibliographic studies have traditionally focused on the classical hydraulic jump. Therefore, the objective of this research was to study the characteristics of the hydraulic jump in a typified USBR II stilling basin, through a physical model. The free surface profile and the velocity distribution of the hydraulic jump developed within this structure were analyzed in the model. To this end, an experimental campaign was carried out, assessing the performance of both, innovative techniques such as the time-of-flight camera and traditional instrumentation like the Pitot tube. The results showed a satisfactory representation of the free surface profile and the velocity distribution, despite some discussed limitations. Furthermore, the instrumentation employed revealed the important influence of the energy dissipation devices on the flow properties. In particular, relevant differences were found for the hydraulic jump shape and the maximum velocity positions within the measured vertical profiles, when compared to classical hydraulic jumps.
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Stahl, Helmut, i Willi H. Hager. "Hydraulic jump in circular pipes". Canadian Journal of Civil Engineering 26, nr 3 (1.06.1999): 368–73. http://dx.doi.org/10.1139/l98-068.
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Hydraulic jumps in conduits containing free surface flow have received practically no attention. This project was conducted to investigate experimentally the main features of such jumps and to obtain limits for conduit choking. The sequent depth ratio is determined in terms of the approach Froude number based on the conventional momentum approach. The lengths of the surface recirculation and aeration zones are also considered. Two different appearances of jumps are discussed and it is demonstrated that jumps with a small approach depth differ from those with a depth larger than about 30% of the conduit diameter. A choking condition is proposed for which conduits are subjected to full pipe downstream flow. Photographs are used to describe the main flow pattern. The results of this study are readily applicable for design.Key words: aeration, conduit choking, hydraulic jump, pipe flow, sequent depths.