Experiments are conducted in a Ø600 mm tank to analyse the 3D motion of buoyant particles in the free-surface vortex flow. The experiments revealed two stages in the particle motion: stage 1 is the helical motion along the vortex air core and stage 2 is the axial motion inside the vortex core. The stage 1 motion is sensitive to the particle’s initial conditions by showing a chaotic behaviour and quantified

Spatially varied flows with increasing discharge can be encountered in several hydraulic systems. The analysis of water surface profiles in such flow conditions is useful for the verification and design of these systems. In this paper, a comprehensive analysis of the possible flow profiles in non-prismatic trapezoidal channels is performed using the method of singular points, by taking into account

For design and management of large scale tunnels, it is important to model the transitions between pressurized and free-surface flows inside them. The pressurized and free-surface flow regimes are separated by a discontinuity with different wave speeds on two sides, which makes efficient and accurate simulations still challenging. A robust and conservative space-time adaptive mesh refinement (AMR)

A multi-phase smoothed particle hydrodynamics (SPH) formulation in combination with a granular rheological model is applied to simulate the 2007 Chehalis Lake landslide and the subsequent tsunami. The model is implemented within the open-source 3D code GPUSPH. The lake geometry is built using the British Colombia Hydro (BCH) topography and bathymetry surveys, and the landslide initial geometry is reconstructed

ABSTRACT The effects of the variation of the viscoelastic pipe material properties on the transient pressure wave propagation are investigated through laboratory and numerical tests. The used experimental set-up consists of a series of a high-density polyethylene (HDPE) pipe with an oriented polyvinyl chloride (PVC-O) pipe. A pulse and a step pressure wave are introduced in the system using an automatically

This paper presents a new sub-grid flood inundation model aimed at high computational performance. The model solves the two-dimensional shallow water equations (SWE) by a Godunov-type finite volume (FV) method that uses two nested meshes. Runtime computations are performed at a coarse computational mesh, while a fine mesh is used to incorporate fine resolution information into the solution at pre-processing

Various transient test-based techniques have been developed for detecting leaks in pipeline systems, and most of these depend on a signal that is reflected by the leak. In field pipes, this signal is easily disturbed by high frequency noise, which can prevent detection. This paper presents a leak detection method using transient pressure damping by energy dissipation from the leak, which is minimally

ABSTRACT Two computational fluid dynamics models were developed to analyse the internal fluid mechanics of an Archimedes screw’s buckets. The models were evaluated against laboratory-scale experimental data, which suggested that they were acceptably accurate. Results of power-generating torque, internal fluid velocities, wall shear stress, and leakage flow rates were all explored with respect to changing

Both the apparent bedload velocity and the backscattering strength measured by acoustic Doppler current profilers could assist bedload assessment in the field. To test this hypothesis, two ADCPs working at three frequencies (3 MHz and 1 MHz, M9; 2 MHz, StreamPro) were deployed simultaneously to measure seven different bedload transport conditions in a laboratory flume. The bedload transport was monitored

This work presents a numerical study of a skimming flow regime in a stepped spillway structure, which is a complex two-phase flow with self-aeration phenomenon. The numerical models employed consist in a hybrid approach capable of switching between interface resolving and interface modelling closures on a local level, and a state-of-the-art volume-of-fluid (VOF) method. A new switch criterion for the

ABSTRACT Measuring flow depths in free-surface turbulent flows can be challenging due to their fast dynamics and the presence of aeration. This study analyses the suitability of a low-cost sensor, the Intel® RealSense™ D435 RGB-D camera, for characterization of a highly aerated case study: the hydraulic jump. As with all instrumentation, special care must be taken to ensure accurate measurements. In

Conventional rectangular side weirs installed along prismatic open-channels may have low efficiency. One practical way to overcome this problem may be to insert the weir in the oblique side of a converging channel. In this paper, the performance of oblique straight side weirs or two-segment single-cranked side weirs inserted in rectangular converging channels are analysed through 3D computational fluid

ABSTRACT Hydraulic characteristics of swirling flow at shaft spillways with an innovative inlet, namely the marguerite-shaped inlet, is investigated based on model experimentation. Detailed measurements of head–discharge relationship, flow regimes, water free-surface profiles, flow circulation, discharge coefficient and threshold and critical submergence depths were performed for shaft spillways with

The present laboratory study used particle image velocimetry (PIV) to measure transitional flow regimes during the jet-flipping process, which is cyclical in the scour hole downstream of a sluice gate with an apron. The transitional vortical structures during jet flipping (both upward and downward) are clearly captured and discussed. Various vortices are formed in the scour hole by two pairs of component

Various empirical equations for mean bed and wall shear stresses have been proposed for smooth rectangular open channels. Considering that the distribution of bed shear and wall shear stresses is affected by the cross-sectional shape, the gravity force based on the flow depth used to non-dimensionalize shear stresses in previous studies is modified to a parameter that includes the width and wetted-perimeter

ABSTRACT Existing pipe-filling models have primarily considered steady friction alone, tending to underestimate pressure attenuation. Various popular unsteady friction models are considered here to simulate pressures within a rapidly filling vertical pipe. Numerical predictions are compared to each other and to experimental results. The models considering unsteady friction better reproduce measured

ABSTRACT This article highlights the theoretical and experimental research of Léopold Escande, conducted in hydraulic engineering. He is considered one of the great European leaders in this field from 1930 to around 1970, when he retired. Numerous students have profited from his knowledge, aware of a person treating them like their father. A number of these students and later collaborators are presented

The processes of sediment transport in high flow intensity are studied through numerical simulation using a coupled CFD (computational fluid dynamics)-DPM (discrete particle method) model with a focus on discussing the co-existence problem of bed load and suspended load and the corresponding sediment concentration distribution. It is shown that for the sediment-laden flows, the components of turbulence

Reflections of the surface waves in hydraulic wave flumes could affect the performance of the common piston, hinged and plunger type wavemakers. This paper proposes a new wavemaker to produce surface waves where the possible reflections are barely able to affect its performance. The proposed wavemaker includes an oscillating paddle at the bottom of the flume where the produced upward flow induces travelling

ABSTRACT Transverse solute mixing across a vegetation generated horizontal shear layer was quantified using laser induced fluorometry techniques for artificial and real vegetation. A two-dimensional finite difference model (FDM) was developed to describe transverse concentration profiles for flows containing transverse variations in velocity and transverse dispersion, from a steady solute input. The

Accurate prediction of the discharge through radial gates is difficult. Existing calibration methods typically provide sufficient accuracy for free flows and submerged flows with jet Froude number at vena contracta larger than 1.7. However, their predictions are poor for submerged flows with jet Froude number less than 1.7. Based on the analysis of experimental data collected by the US Bureau of Reclamation

A numerically-based approach is used to obtain a size selection formula for the riprap stone part of the apron used to protect wing-wall abutments against erosion. Several series of simulations with a given mean riprap diameter are conducted to estimate the maximum bed shear stress over the riprap apron and then the maximum (critical) Froude number at which riprap stones will resist shear failure by

A new airborne river surface flow measurement technique is presented, called Airborne Feature Matching Velocimetry (AFMV). It uses matchings of characteristic image features for orthorectification and velocimetry. Riparian matching points with an arbitrarily chosen base image serve to find individual projective transformation matrices to stabilize airborne video recordings. Transformed matching points’

Conventional streamflow monitoring methods entail one-to-one relationships between two flow variables obtained by combining direct flow measurements with statistical analyses. These relationships (i.e. ratings) are used to monitor both steady and unsteady flows despite that in the latter cases the flow variables display an inherent hysteretic behaviour. Such behaviour is prominent if the wave passing

(2020). Statistical analysis methods for transient flows – the dam-break case. Journal of Hydraulic Research: Vol. 58, No. 6, pp. 1001-1004.

(2020). Statistical analysis methods for transient flows – the dambreak case. Journal of Hydraulic Research: Vol. 58, No. 6, pp. 1004-1005.

ABSTRACT Solitary waves are often used to replicate tsunami waves and, therefore, the study of their propagation and interactions with structures could help to understand the impacts of tsunami waves on infrastructures. This paper presents a numerical model that uses the level-set framework for simulating the propagation of solitary waves and their interactions with structures using the immersed boundary

ABSTRACT In this paper, the movement of the water surface with macroscopic particles during a dam break flow using the volume of fluid (VOF) methods, the discrete phase model (DPM) and macroscopic particle model (MPM) models were numerically simulated. To solve this equation system numerically, the PISO numerical algorithm was chosen. The accuracy of the 3D model and the selected numerical scheme were

Predicting piping failure is essential to the safe assessment of dikes and dams since erosion is one of the main causes of serious hydraulic system failure. The objective of this paper is to describe the groundwater flow in porous media with the Shields–Darcy piping model, and discuss its differences with the current Sellmeijer model, especially for prototype situations. The solution of the Laplace

ABSTRACT This paper presents the results of the monitoring and analysis of the dynamic behaviour of the Gorino Ferrarese (Ferrara, Italy) water distribution system. The network is subjected to ordinary operational conditions, (i.e. no manoeuvres on pumps or valves are considered), the aim being to show that user demand may generate frequent and not negligible pressure variations. Pressure and discharge

The aim of this work is to develop an original semi-coupled approach for solving the Saint-Venant and Exner equation system. The shallow-water equations are solved first to calculate the full evolution of flow fields, and then the Exner equation is solved to model the morphodynamic response. The numerical method is based on a projection method, which consists in combining the momentum and continuity

Multiple types of 1-D flow models simulate unsteady pipe network hydraulics. Water hammer models capture highly transient hydraulics, whereas incompressible flow formulations are more computationally efficient. Recent efforts to balance the accuracy–efficiency tension have been limited by numerical instability, model applicability, and inefficient solution schemes. Here, a novel adaptive hybrid transient

Entrainment of density flows is a key parameter in constructing predictive models of global climate, ocean flows, and turbidity currents. Our numerical experiment, which included 10 subaqueous dilute density flows with a steady sustained inflow (SSI) on a 2D channel bed slope varying from 0.1° to 90°, showed that in the slope range of 0.1–20°, there is a linear relationship between the ambient fluid

ABSTRACT Accurate calculation of air demand is fundamental in the design of air ducts in a spillway tunnel. However, it was often underestimated by empirical formulas in previous studies. In this paper, an air–water stratified flow model, in which the air and water are coupled by a new interfacial shear stress formulation, is proposed. The model is verified by using prototype data and numerical CFD

Under large unit discharges, cavitation damage may occur and energy dissipation may remarkably decline in stepped chutes due to absence of air entrainment. Herein, a pre-aeration device, entraining air by contracting the flow locally by walls without special air vent, is proposed for increasing the maximum available unit discharges. The test results demonstrate that the aerator proposed in this paper

This study investigates the effects of wildlife activities by beavers, muskrats, gophers, and ants on seepage through Barr Lake, Commons Pond, Lake Elizabeth, Village Pond, and Walden Place Dams in South Carolina, USA, using a numerical seepage model. Data was collected from all dam sites for geotechnical testing, and observations were made for animal activities. The laboratory results were used for

A model for the subsurface flow and associated oxygen transfer induced by surface flow and slip velocity is presented in a gravel bed river. The shear velocity (U *) and hydraulic conductivity (K) were used to characterize the surface flow and subsurface flow, respectively. The subsurface flow field was described by using the Darcy and the Brinkman equations. The interaction between surface and subsurface

The transient behaviour of the pump-turbine in load rejection is very complex, and slight changes in runner blade shape may have great influence on it. To understand the underlying flow mechanisms, the load rejection processes of two model pump-turbines with the same specific-speed but different in the runner blade inlet shape were investigated by a three-dimensional numerical simulation method. The

ABSTRACT Numerical models are used increasingly to tackle aerated flows for example in spillway design. However, these models are usually empirical and often lack thorough calibration. Herein a mixture model is calibrated with experimental data on uniform aerated flow from literature. A commercial code was used to solve the mixture Reynolds-averaged Navier–Stokes equations. Air entrainment was modelled

ABSTRACT Flow patterns around three widely used instream rock structures in an open-channel flume were investigated using high-resolution large-eddy simulations. Specifically, rock vanes at two different installation angles, a J-hook vane, and bendway weirs at two different angles, with realistic geometries, were studied. Velocity fields in the wake of these instream structures were measured using

A series of experiments were conducted beneath simulated partial ice covers to investigate the turbulent flow behaviour using a particle image velocimetry system. The velocity data were used to assess predictive capabilities of some bed shear stress models developed for open channels. Specifically, the abilities of the Ludwieg–Tillmann, quadratic stress law and Prandtl's seventh power law techniques

(2020). Correction. Journal of Hydraulic Research. Ahead of Print.

Self-cleansing is a hydraulic design concept for drainage systems for mitigation of sediment deposition. Experimental studies in the literature have mostly been performed in circular channels. In this study, experiments were conducted in five cross-section channels: trapezoidal, rectangular, circular, U-shape and V-bottom to investigate the non-deposition condition of sediment transport in rigid boundary

In this paper, the Spalart–Allmaras turbulence model, very popular for compressible aerospace applications, is adapted for incompressible free surface environmental flows. The Spalart–Allmaras model is a Reynolds-averaged Navier–Stokes model which solves for one transport equation of a viscosity-like variable. Besides its efficiency and reasonable computational cost, the model can take into account

Owing to the complexity of the load rejection process, the accompanied complex low frequency pressure fluctuations and their sources have not been determined. Herein, the load rejection transient process of a pump-turbine was simulated with a three-dimensional (3-D) large eddy simulation method and a dynamic mesh technology. The simulation results were validated against the experimental data. Through

This paper presents a vegetated flow and sediment transport model for investigating flow–vegetation–sediment interactions. Vegetation-induced turbulence is simulated by a k − ε turbulence closure, in which shear and stem-scale wake turbulent kinetic energies are solved separately. The model simulates both unidirectional and oscillatory flows as well as turbulence structures reasonably well with the

We present an experimental analysis of hydraulic roughness variations due to changes in alluvial cover in a mixed bedrock-alluvial meandering channel with larger bedrock roughness than alluvial roughness. Three sets of experiments were conducted in a highly sinuous flume: one with bare bedrock, and two with enough sediment to cover 21% and 78% of the bedrock respectively. We compare our results with

ABSTRACT We present an experimental analysis of hydraulic roughness variations due to changes in alluvial cover in a mixed bedrock-alluvial meandering channel with larger bedrock roughness than alluvial roughness. Three sets of experiments were conducted in a highly sinuous flume: one with bare bedrock, and two with enough sediment to cover 21% and 78% of the bedrock respectively. We compare our results

This paper presents a vegetated flow and sediment transport model for investigating flow–vegetation–sediment interactions. Vegetation-induced turbulence is simulated by a k − ε turbulence closure, in which shear and stem-scale wake turbulent kinetic energies are solved separately. The model simulates both unidirectional and oscillatory flows as well as turbulence structures reasonably well with the

Gravel-bed roughness structures for an unworked bed and a water-worked bed are analysed at different topographic scales measuring the bed surfaces by a 3D terrestrial laser scanner in a laboratory flume. The study represents a novel contribution in assessing the role of water-work on a uniform gravel-bed, demonstrating the development of small-scale bedforms (i.e. clusters). To support these observations

Simulations of shallow-water flows in an open channel with vegetation are considered. The simple formulation of bulk resistance makes numerical realization of vegetation straightforward. Stem-scale eddies due to individual plants are not modelled. While the vegetation resistance parameterization has been frequently used, few studies exist that comprehensively evaluate the modelling skills of such a

(2020). Correction. Journal of Hydraulic Research. Ahead of Print.

This article concerns the turbulent flow of Herschel–Bulkley slurries through circular horizontal pipes; in particular, that of concentrated domestic slurry obtained upon separation of domestic waste water and reduction in the use of water for domestic purposes. Experiments with a rheologically equivalent clay (kaolin) slurry indicated a non-Newtonian behaviour of the Herschel–Bulkley type. A modified

Debris flows are typical two-phase flows that commonly occur with entrainment. By involving sediment materials, the fluid viscosity of debris flow may change significantly along with the variety of solid volume fraction, which further influences debris flow routing. To address this issue, a two-phase model is incorporated with a correlation for the apparent viscosity of the mixture and an entrainment

Hydropower tunnels are generally subject to a degree of rock falls. Studies explaining this are scarce and the current industrial standards offer little insight. To simulate tunnel conditions, high Reynolds number flow inside a channel with a rectangular cross-section is investigated using particle image velocimetry and pressure measurements. For validation, the flow is modelled using large-eddy simulation

We present an experimental study of natural hyperconcentrated flows of fine sediment from Draix-Bleone observatory. Suspensions of volumic concentration ranging from 29 to 44% were tested in a rheometer and exhibit a Herschel–Bulkley behaviour. Suspensions of volumic concentration ranging from 0 to 31% were tested in flume experiments with varying slope and discharge. Velocity profile measurements

The 2D shallow water equations are often solved through finite volume (FV) methods in the presence of irregular topography or in non-rectangular channels. The ability of FV schemes to preserve uniform flow conditions under these circumstances is herein analysed as a preliminary condition for more involved applications. The widely used standard Harten-Lax-Van Leer (HLL) and a well-balanced Roe method

For a channel with a constant discharge, the characteristics of the surge wave entering a junction are obtained from the classical Stoker solution, and then the effect of the junction is analysed by applying the momentum and mass conservation equations. Experimental cases involving different combinations of the tributary lake height and the main channel discharge were tested, and measurements show

Air supply to free-surface water flows in tunnels is a key safety issue for high-head dams. The present study analyses the effects of approach water velocity and area residual of tunnel cross-section on air demand, using the volume of fluid (VOF) method in combination with the k–ε turbulence model. For a tunnel area residual less than 0.4, the attenuation of air velocity above the free-surface water

In the analysis of water distribution networks (WDNs) facing uncertainty, fuzzy set theory is suggested as an applicable stochastic analysis approach when the probability distributions of the information are not available. This technique can recognize the extreme values of unknown variables when uncertain input information varies between pre-specified extremes. Current approaches proposed in the literature