Journal of Hydraulic Research (J HYDRAUL RES )

Publisher: International Association for Hydraulic Research; International Association of Hydraulic Engineering and Research

Description

Published bimonthly, this is a leading international scientific Journal for peer-reviewed research and technical developments in hydraulics and water science. All papers are reviewed by at least two members of the Editorial Board, consisting of internationally renowned experts in their specific field. The Journal is free of charge for corporate and individual members.

  • Impact factor
    1.04
    Show impact factor history
     
    Impact factor
  • 5-year impact
    1.15
  • Cited half-life
    0.00
  • Immediacy index
    0.23
  • Eigenfactor
    0.00
  • Article influence
    0.50
  • Website
    Journal of Hydraulic Research website
  • Other titles
    Journal of hydraulic research, Journal de recherches hydrauliques, Journal of the I.A.H.R., Journal de l'A.I.R.H., IAHR/AIHR journal
  • ISSN
    0022-1686
  • OCLC
    3910556
  • Material type
    Periodical
  • Document type
    Journal / Magazine / Newspaper

Publications in this journal

  • Journal of Hydraulic Research 09/2014;
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    ABSTRACT: This work presents an investigation on the effects of spatial and temporal averaging processes (filtering) implemented in Acoustic Doppler Velocimeter (ADV) on the computations of the turbulent kinetic energy, velocity variances, and Reynolds shear stresses. The averaging processes are implemented in the ADV technology in order to reduce the noise level inherent in acoustic measurements. A conceptual model, simulating the ADV operation and the turbulent flow field, is developed to assess the filtering effects on the turbulence parameter estimates of sampling volume heights, recording frequencies, and distances from the sampling volume to the channel bottom. The results of the conceptual model are compared with experimental data. The findings provide a criterion to examine the capability of ADV to characterize turbulent flows using different sampling configurations.
    Journal of Hydraulic Research 08/2014;
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    ABSTRACT: Axially stretched free-surface vortices occur at low-head hydropower intakes under specific flow and geometric conditions. When they are sufficiently strong, they can harm performance or cause premature failure of mechanical components such as turbine blades or guide vanes. Laboratory-scale experimental models are currently used to assess the risk of vortex formation during the design phase, but uncertainty remains as to how vortex characteristics translate from the laboratory scale to the much larger scale of an actual hydropower plant. This paper proposes a semi-empirical model that roughly predicts how the approach flow and intake geometry determine the key vortex characteristics (the core radius, bulk circulation and the depth of the free surface depression). The model is developed using detailed velocity measurements of the approach flow and the flow inside the vortex in a laboratory-scale physical model, using analytical models and insights drawn from previous work.
    Journal of Hydraulic Research 07/2014; 52(4).
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    ABSTRACT: The dynamic importance of spanwise vorticity and vortex filaments has been assessed in steady, uniform open-channel flows by means of particle image velocimetry. By expressing the net force due to Reynolds’ turbulent shear stress, [Inline formula], in terms of two velocity–vorticity correlations, [Inline formula] and [Inline formula], the results show that both spanwise vorticity [Inline formula] and the portion of it that is due to spanwise filaments make important contributions to the net force and hence the shape of the mean flow profile. Using the swirling strength to identify spanwise vortex filaments, it is found that they account for about 45% of [Inline formula], the remainder coming from non-filamentary spanwise vorticity, i.e. shear. The mechanism underlying this contribution is the movement of vortex filaments away from the wall. The contribution of spanwise vortex filaments to the Reynolds stress is small because they occupy a small fraction of the flow. The contribution of the induced motion of the spanwise vortex filaments is significant.
    Journal of Hydraulic Research 07/2014; 52(4).
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    ABSTRACT: An experimental investigation is carried out to determine the trajectory, spread, dilution and cross-sectional flow structures of non-buoyant oblique jets released in a moving ambient, covering initial discharge angles from 10 to 90°. For each angle, measurements of the side view and plan view integrated concentration fields are obtained. The double-Gaussian assumption is used to characterize the cross-sectional concentration profiles, which gradually change from the axi-symmetric Gaussian of the weak-jet region to the double-vortex pair structure of the momentum puff region. In the weakly-advected region, the spread is similar to that of the jet in a stagnant ambient, while in the strongly-advected region a new spread relationship is obtained based on the double-Gaussian assumption. The spread relationships are used in an existing integral model, resulting in predictions for the trajectory and dilution that are a good match for the experimental data in the weakly- and strongly-advected regions.
    Journal of Hydraulic Research 07/2014; 52(4).
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    ABSTRACT: A series of plane dike overtopping laboratory tests is reported, in which the effect of sediment mixture on the breach process is investigated. Three different sediment mixtures were tested, in addition to the reference dike consisting of uniform non-cohesive sediment. No sealing elements or surface protection were applied. The adopted constant reservoir inflow led to a falling reservoir scenario. The experiments demonstrate that the grain size distribution has a small effect on the overall breach process within the given test range, as the hydraulic conditions during the dike breach are much above the sediment entrainment condition. No increased erosion resistance was observed for the sediment mixtures. Therefore, the mean sediment diameter adequately describes the non-cohesive material characteristics and general dike-breach features in laboratory scale can be investigated using uniform material. This finding is significant both for laboratory experimentation and for prototype dike construction.
    Journal of Hydraulic Research 07/2014; 52(4).
  • Journal of Hydraulic Research 07/2014; 52(4).
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    ABSTRACT: In hydraulic research, numerical modelling of complex flows is essential for managing water risks. High-resolution finite volume schemes have become popular for shallow water flow modelling due to their mass and momentum balance characteristics and their ability to capture shocks. These methods use slope limiters to suppress numerical oscillations near discontinuities. However, one-dimensional limiters do not assure numerical accuracy in multidimensional applications, occasionally leading to excessive or insufficient numerical dissipation. For this reason, a multidimensional limiting process (MLP) was developed for oscillation control in multidimensional compressible flows. In this paper, we implement MLP on adaptive quadtree grids for shallow water flow simulations and compare MLP performance with simulations using conventional limiters. Four simulation cases show that MLP outperforms conventional limiters, and yield more accurate and stable solutions on adaptive quadtree grids. The capability of MLP for oscillation control is more noticeable on quadtree than on uniform grids.
    Journal of Hydraulic Research 07/2014; 52(4).
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    ABSTRACT: The paper describes two different ways of defining the terrain roughness in smoothed particle hydrodynamics (SPH) simulations performed with the Tis Isat model, developed at the University of Ljubljana. The model introduces into the SPH method a non-discrete boundary condition with friction. Two basic definitions of terrain roughness are used: (a) as a hydraulically smooth wall, where roughness was controlled by the wall–particle eddy viscosity coefficient; and (b) as a hydraulically rough terrain by elevating the mesh-nodes. The undertaken SPH simulations relate to a dam break at the upper storage reservoir of the pumped-storage hydro power plant Kolarjev vrh in Slovenia. For the first time, such study was performed on a real topography. Water depths at the gauges along the valley were compared with measurements on a physical model and to results obtained using a finite volume (FV) model. The comparison showed satisfactory agreement with the measurements, which are comparable with the FV model simulations.
    Journal of Hydraulic Research 07/2014; 52(4).
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    ABSTRACT: Engineers frequently use physical scale models of hydropower intakes to assess and minimize the occurrence of harmful free surface vortices. The impact of surface tension, viscosity and turbulence on the scaling behaviour of the vortices is examined here using an analytical free surface vortex model developed from measurements in a laboratory-scale hydropower intake. First, the effect of surface tension on the free surface depression is computed using a finite-difference model over a wide range of depression scales and shapes. The impact and scaling behaviour of surface tension are found to be qualitatively different depending on whether the depression is dimple- or funnel-shaped. The influence of viscosity on scaling predicted by the analytical vortex model contradicts trends recorded by previous authors, which suggests that additional processes such as turbulent diffusion may play a significant role at larger scales. Scale effects due to the interplay of viscosity and turbulence require further investigation, whereas those due to surface tension are fairly easily quantified and predicted.
    Journal of Hydraulic Research 07/2014; 52(4).
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    ABSTRACT: Intake free-surface vortices can cause efficiency losses, flow fluctuations and even structural damages. Experiments were performed to examine the effect of entrance shapes on the critical submergence. Seven entrance shapes were devised and tested, including a square-edged, a bell-mouthed, three symmetrical conical and two conical profiles with eccentricity. The focus of the study was on a range of Froude numbers from 0.25 to 0.65. The square-edged shape appeared to show the highest local head-loss compared to other shapes. Steady counter-clockwise vortices characterize all the intake profiles except in a narrow water tank. The experiments show both discrepancy and similarity between the intake profiles. The critical submergence of the bell-mouthed intake is lower when compared to the square-edged shape. For the other profiles, it is proportional to the Froude number. A closer sidewall may lead to larger critical submergence in the case of weak circulations. The results demonstrate that the intake-entrance profile has an important effect on the critical submergence.
    Journal of Hydraulic Research 07/2014; 52(4).
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    ABSTRACT: An existing solution method for the quasi two-dimensional model of transient flow in pipes has already been recognized as accurate, robust, and consistent with the physics. Its main disadvantage – numerical inefficiency, has recently been considerably reduced by introducing an improved solution procedure. This paper proposes a new and even more efficient solution procedure. The proposed method gives results that match the results of existing methods, but requires approximately 10% less central processing unit time than the improved procedure.
    Journal of Hydraulic Research 06/2014;
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    ABSTRACT: This paper reports the results of detailed numerical simulations of the flow over a submerged bridge. The method of Large Eddy Simulation (LES) is applied, which allows elucidation of the instantaneous flow and an accurate quantification of its turbulence statistics. The in-house LES code employs a free surface algorithm based on the Level Set Method (LSM) to determine the complex water surface profile over the bridge, which is validated with data from a physical model of the bridge under analogous flow conditions. Numerically predicted water surface profiles showed good agreement with measured data. The water surface resembles that of the flow over a broad-crested weir with a plunging nappe and a standing wave downstream of the bridge. The mean flow is characterized by a multitude of complex flow features including horizontal recirculation zones upstream and downstream of the bridge abutment and vertical recirculation zones of the separated plunging flow. The latter influences significantly the near-bed turbulence and the bed shear stress.
    Journal of Hydraulic Research 03/2014;
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    ABSTRACT: Hydraulic turbines are frequently used to maintain electrical grid parameters. An angular movement of the guide vanes (GVs) during transients such as load acceptance and rejection within short time raised significant concerns for increased wear and instabilities. The present work focuses on the pressure variations in a high-head Francis turbine during the transients. Six transient conditions were investigated including time-domain rotor–stator interaction. The measurements in the vaneless space and runner indicated the presence of unsteady vortical flow during transients. The vortices travelled to the runner and affected the flow in the blade channels. The GVs angular movement increases the pressure difference between the pressure and suction sides of the blade. The largest pressure variation was observed during the partial load rejection at the trailing edge of the blade. Preliminary results indicated that an appropriate closure of the GVs may minimize large pressure fluctuations in the runner.
    Journal of Hydraulic Research 03/2014; 52(2):1-15.