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The Journal contains scientific and technical material of broader interest in the areas of theoretical, experimental and computational hydraulics and fluid mechanics in various fields of application (rivers, coasts, environment, structures and industrial flows). This may also include results of field studies and interdisciplinary studies. Further included is publication of state-of-the-art papers, information which is suitable for the end-user (design and consultancy) and forum articles. Discussions to papers and technical notes are welcomed. The scope of the Journal covers the fields in which IAHR is active.
The Journal of Hydraulic Research has been published (currently six issues per year) since 1964 by IAHR and is distributed to all IAHR Members as part of the Membership Subscription, together with the IAHR HydroLink newsletter. JHR is published in print and electronic format. Abstracts are available on-line from 1996,and Full papers from 2001.
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Abstract of Papers -
JHR
Volume 47
Issue 5
| Investigation of rapid filling of poorly ventilated stormwater storage tunnels |
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| by JOSE G. VASCONCELOS, STEVEN J. WRIGHT |
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Vol: 47 / Issue: 5
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| Below-grade stormwater storage tunnels are designed to provide relief for collection networks during intense rain events. Air must be evacuated as the tunnel fills and, depending on the system geometry, the air may become pressurized. This research presents an investigation on various ways that the air pressurization influences the water flow. The investigation used an experimental apparatus consisting of a horizontal 14.8 m long, 94 mm diameter acrylic pipeline with various degrees of air ventilation. The experiments were primarily conducted to explore two features of the flow termed pre-bore motion and the interface breakdown. Experimental measurements include flow velocity, air and water pressure, and flow depth. The experimental results were compared to the predictions of a numerical model based on the Saint-Venant equations that handles the flow regime transition and the possibility of air pressurization. The numerical predictions agree well with the experimental observations and provide an explanation for the interface breakdown occurrence. |
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| Influence of design parameters on throttling efficiency of cylindrical and conical vortex valves |
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| by PATRYK WÓJTOWICZ, ANDRZEJ KOTOWSKI |
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Vol: 47 / Issue: 5
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| Selected hydraulic test results of cylindrical and conical vortex valves in a pilot-plant scale are presented to discuss the effects of the geometric parameters and the spatial orientation of a vortex chamber. Tests performed include the effects of the inlet and outlet diameters, swirl radius, chamber height and diameter on the hydraulic characteristics. A novel, universal variable K, describing the geometry of vortex valves and grouping their geometrical parameters, is introduced. This constant K increases the quantitative accuracy of the relationship between the discharge coefficient and the geometrical parameters. A test methodology for hydrodynamic vortex regulators has been developed and was applied to environmental engineering, based on dimensional analysis. This research presents the empirical equations enabling to predict the discharge coefficient according to the geometrical parameters of the devices. The investigated relationships allow for a rational parameter selection for hydrodynamic vortex regulators. |
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| Analytical model of supercritical flow in rectangular chute bends |
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| by MAHNAZ GHAEINI HESSAROEYEH, AHMAD TAHERSHAMSI |
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Vol: 47 / Issue: 5
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| An analytical model to predict supercritical bend flow in a rectangular chute is developed. The governing differential equations consisting of the two-dimensional depth-averaged Euler and continuity equations, are linearized by the method of perturbation, and solved analytically by the Laplace transform method considering appropriate boundary conditions. The free surface profile in the chute bend is obtained. The proposed model is verified by comparing the results with the available experimental data and the reported theoretical expressions for the free surface profile along the outer chute wall. Comparisons indicate a reasonable agreement between the results obtained for the maximum flow depth along the outer chute wall. However, there is a lag in predicting the location of maximum flow depth. The present model is successful if the flow does not separate from the inner chute wall. |
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| Curved-streamline transitional flow from mild to steep slopes |
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| by OSCAR CASTRO-ORGAZ, WILLI H. HAGER |
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Vol: 47 / Issue: 5
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| 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 curvilinear-streamline feature involving a continuous free surface profile, and a rapid variation of the bottom pressure profile. Herein, the transition from a horizontal to a steeply sloping rectangular channel reach is investigated to analyze the application range of the Bousssinesq-type equation. Slope breaks with a rounded transition from the brink section to the tailwater channel are considered and compared with the potential flow solution based on the Laplace equation. The Boussinesq-type equation is further compared with test data for a steep downstream slope to investigate the strong curvilinear gravity effect. A singular point analysis is also compared with the Boussinesq approach. The generalized momentum equation for curvilinear flows is developed and compared with the results pertaining to the energy concept. |
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| Modelling dike breaching due to overtopping |
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| by LUKAS SCHMOCKER, WILLI H. HAGER |
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Vol: 47 / Issue: 5
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| 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 plans and to design early warning systems and hazard maps. Laboratory tests of breach processes are related to scaling issues currently not understood. Therefore, a series of plane dike breach tests due to overtopping were conducted to examine model limitations. All dikes were of trapezoidal shape, consisted of uniform noncohesive sediment and neither contained a core nor a surface layer. The temporal dike breach progress was optically recorded to allow for a detailed analysis of the sediment and water surfaces. A systematic variation of both the dike dimension and the sediment diameter resulted in basic findings relative to: (1) Test repeatability; (2) Side wall effect; and (3) Scale effects. The results indicate definite minimum dimensions for both the dike height and width, sediment diameter and overtopping discharge. |
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| Turbulence structure and coherent motion in meandering compound open-channel flows |
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| by MICHIO SANJOU, IEHISA NEZU |
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Vol: 47 / Issue: 5
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| Meandering compound open-channel flow is of high interest in river engineering and flood disaster. In particular, cross-sectional secondary currents develop significantly associated with an interaction between meandering inbank main-channel flow and straight overbank floodplain flow. These currents promote mass and momentum exchanges between them, as well as sediment transport and bed erosion. Further, organized motions may be generated in the same manner as typical horizontal vortices in straight compound channels. However, there is limited detailed information on the generation process of organized motion and secondary currents. This study focuses on the 3D structure of horizontal coherent motion and its advection property in the channel-transition zone from the straight to meandering compound open-channel flows by using a multi-layer scanning PIV, and compares them with those of continuous meandering channel flows. A strong relation between the horizontal vortices and secondary currents was obtained, resulting in a phenomenological flow model. |
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| Investigation of circular jets in shallow water |
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| by JOHN P. RAIFORD, ABDUL A. KHAN |
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Vol: 47 / Issue: 5
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| The combined influence of the free surface and the bed on the flow characteristics of circular turbulent jets issued at mid-plane into shallow, stagnant ambient fluid is investigated using a physical model study. A total of nine experiments have been performed under different Reynolds numbers and submergence ratios. The velocity profiles in the horizontal plane are found to be similar, while the velocity profiles in the vertical plane are similar only in the near zone. The growth rate of velocity profiles in the horizontal plane consists of two distinct regions for low submergences, namely regions 1 and 2, corresponding to a mild and steep growth rates, respectively. The growth rate in the vertical plane within the near zone is linear. The local maximum velocity decay rate follows the free circular jet in the near zone and wall or surface jet in the far zone. |
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| A simple estimation of the growth rate and equilibrium size of bedforms created by a turbulent wall jet |
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| by DAVID F. HILL, BRIAN D. YOUNKIN |
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Vol: 47 / Issue: 5
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| A simple procedure for predicting the time evolution and equilibrium size of the two dimensional bedform created by a turbulent wall jet is presented. The model applies to a planar jet discharging flush with and parallel to an initially horizontal bed of cohesionless sediment. Additionally, the water is assumed to be deep relative to the initial jet thickness. The model is developed using existing free- and wall-jet boundary layer relations and existing sediment incipient motion and bedload transport equations. The model is validated against live-bed experiments from previous studies and from a new set of laboratory experiments. The agreement between the predictions for and observations of equilibrium size is quite good. The agreement regarding the time evolution is also good. These results suggest that several key characteristics of jet-induced bedforms are captured with a limited physical approach. |
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| Turbulence statistics of flow over isolated scalene and isosceles triangular-shaped bedforms |
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| by BIJOY S. MAZUMDER, DIBYENDU K. PAL, KOELI GHOSHAL, SATYA P. OJHA |
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Vol: 47 / Issue: 5
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| The objective of this research is to examine the turbulent flow characteristics over artificial waveform structures and to compare turbulence between two types of isolated geometries. Measurement of turbulent velocity components have been performed over the respective structures of equal crest height and length at the Fluvial Mechanics Laboratory (FML) of the Indian Statistical Institute, Calcutta. The velocity data were analyzed to determine the relative importance of mean flows, Reynolds stresses and the contributions of burst-sweep cycles. The difference in the sizes of the separation zone for these two cases makes significant differences in the mean flow and turbulence. The motivation of this study is to identify the spatial changes of flow and turbulent events over these structures, and to gain better insight in the flow physics, which are different conditions for the process of sediment transport. |
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| Analysis of plunging phenomena |
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| by ALBERT DAI, MARCELO H. GARCIA |
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Vol: 47 / Issue: 5
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| A dense inflow from a river into a lake or reservoir initiates gravity currents through a plunging process with intense mixing. The classic two-control-volume theory for the analysis of plunging phenomena has been recently corrected. In particular, the design of one of the two control volumes does not follow physical principles and has undesirable implications. Herein, a generalized theoretical framework is developed for the analysis of plunging flows. Two general cases are considered to clarify the effects of the bottom slope and the inflow densimetric Froude number on the plunge condition. It is demonstrated that the relations between the dimensionless parameters characterizing the plunging phenomena in these two cases are generically different. The present theory is compared with the two-control-volume theory, the latter of which only partially explains the influence of the inflow densimetric Froude number. Good agreement between the present theory and reported data is found. |
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| Scalar flux modeling of solute transport in open channel flows: Numerical tests and effects of secondary currents |
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| by HYEONGSIK KANG, SUNG-UK CHOI |
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Vol: 47 / Issue: 5
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| Numerical experiments involving various algebraic scalar flux models for solute transport in open channel flows are presented. Five algebraic scalar flux models including these of Daly and Harlow, Abe and Suga, Suga and Abe, Sommer and So, and Wikstrom et al. are tested. For the flow computation, a Reynolds stress model is used. The models are applied to laboratory experiments of solute transport in rectangular and compound open channel flows. The performance of each model is evaluated both qualitatively and quantitatively. It is found that Daly and Harlow's model, although simple, predicts the solute transport most accurately. Further, with reference to the simulation results, the roles of the Reynolds fluxes and secondary currents in the solute transport equation are investigated. It is found that the Reynolds fluxes and secondary currents reduce and move the peak concentration, respectively. |
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| Application of ant colony optimization to optimal design of open channels |
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| by VAHID NOURANI, SIAMAK TALATAHARI, PARVIZ MONADJEMI, SIMIN SHAHRADFAR |
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Vol: 47 / Issue: 5
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| Artificial open channels are expensive infrastructure in terms of material, construction and maintenance and application of optimization models has a great role in minimizing their cost. Two optimization approaches for the cross-sectional design are compared. In the first stage, an equivalent roughness coefficient is considered without any sectional division according to the Manning equation. Then, in the second stage, the horizontal velocity variation over the cross-section is taken into account by dividing the channel into three segments. Both, ant colony optimization, as a new heuristic approach, and the genetic algorithm method have been used to solve the non-linear optimization problem. Considering the obtained results for different design variables, the optimal and appropriate cross-section is proposed for composite trapezoidal open channels by the second model by considering horizontal velocity variation. Furthermore, the efficiency and capability of the ant colony optimization are examined to solve and analyze the optimal design models. |
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| Simplified theory of Archimedean screws |
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| by GERALD MÜLLER, JAMES SENIOR |
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Vol: 47 / Issue: 5
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| The Archimedean screw pump is one of the oldest hydraulic machines. Today, it is employed in pumping as well as - operating in reverse - in an energy conversion role. Despite its age, no consistent theory links the screw’s geometry with its mechanical efficiency. Based on geometrical parameters and an idealised energy conversion process for one turn of the helix, a theoretical model is developed and compared with experimental results. Theoretical maximum efficiencies were found to be a function of the screw’s geometry and matched reported experimental results well. The statement that the efficiency of a screw is a function of losses only could not be confirmed. |
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| 3D modeling of non-uniform sediment transport in a channel bend with unsteady flow |
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| by Tim Fischer-Antze, Nils Rüther, Nils R.B. Olsen, Dieter Gutknecht |
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Vol: 47 / Issue: 5
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| A fully three-dimensional non-hydrostatic model was applied to compute the water flow and morphodynamic processes in a laboratory flume. The experiments provided data for bed deformation and grain sorting processes in a 180° channel bend. The data were used to investigate the performance of different sediment transport approaches. The original van Rijn formula for uniform sediments was compared with two advanced nonuniform sediment formulas that considered the interaction between individual grain sizes by defining hiding-exposure approaches. The results showed that the default configuration of the model was able to predict bed deformations and grain sorting processes with satisfying magnitude and trend. However, the default approach considerably overestimated the bar evolution. The computed results improved significantly when applying any of the introduced hiding-exposure approaches, representing better the physical mechanisms of the hiding-exposure effect. This study shows that the present numerical model is able to predict the morphodynamic bed changes in a flume of nonuniform sediments with good agreement if appropriate sediment formulations are used. |
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| A model of average velocity in oscillating turbulent boundary layers |
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| by JAAK HEINLOO, ALEKSANDER TOOMPUU |
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Vol: 47 / Issue: 5
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| A model to calculate the vertical distribution of the average velocity in the oscillating turbulent boundary layer forced by the overlaying oscillating free flow is discussed. The model is founded on the Rotationally Anisotropic Turbulence theory. The oscillating boundary layer is treated within the approximation of average velocity depending on the time and vertical coordinate only. The description results in an analytical expression for the flow velocity analogous to the expression for the flow velocity in the boundary layer of oscillating pipe flow. The resulting expressions for the vertical velocity profile are compared with respective laboratory data obtained in two tests of an oscillatory water tunnel experiment. It is shown that similar to the description of oscillating flow in tubes, the outcome of the suggested model with the appropriate values of the model parameters matches the measured velocity data reasonably well. |
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| Plunging conditions of two-dimensional negative buoyant surface jets released on a sloping bottom |
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| by Masamitsu Arita and Masanori Nakai, Journal of Hydraulic Research, IAHR, 2008, 46(3), 301-306 |
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Vol: 47 / Issue: 5
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| Discussers:
a) Albert Dai, Marcelo H. Garcia,
b) Reply by the Authors |
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| Air uptake along the lower nappe of a spillway aerator |
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| by Lima, A.C., Schulz, H.E., Gulliver, J.S., Journal of Hydraulic Research, 2008, 46 (6), 839-843 |
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Vol: 47 / Issue: 5
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| Discussers:
a) Henry T. Falvey
b) Reply by the Authors |
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| Laboratory measurements of 3-D flow patterns and turbulence in straight open channel with rough bed |
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| by Rodriguez, J.F., Garcia, M.H., Journal of Hydraulic Research, 2008 46(4) 454-465 |
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Vol: 47 / Issue: 5
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| Discussers:
a) Brian J. Belcher, James F. Fox
b) Reply by the Author |
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