The current research focuses on the analysis of different dynamic effects of an air pocket located at mid-pipe length on transient pressures based on experimental data. Different flow rates and air pocket volumes are analysed. Several features are identified in the pressure-head signal associated with the air pocket: initial pressure drop, higher maximum overpressure peaks, increased pressure wave

Previous research has shown that the inflow conditions upstream of hydraulic jumps can affect flow aeration, bed pressures and turbulence. However, studies of the effects of inflow conditions on free-surface properties have not been conclusive and have lacked a comparison of partially and fully developed inflow conditions. Detailed measurements of the free-surface features in fully aerated hydraulic

ABSTRACT Cavitation erosion is a fundamental concern in many fields of engineering, e.g. the flow separation zone in high speed flow and the blade area of hydraulic machinery. However, the influence of the physical characteristics of the environmental medium in these engineering facilities on cavitation erosion is still unclear. In this paper, we adopted underwater low-voltage discharge technology

This study presents experimental investigations of entrainment events of a single sediment particle resting in a small pocket on a smooth bed in an open channel flow. The data were acquired with a tomographic particle tracking velocimetry system. The shake the box algorithm, a spatially high resolved Lagrangian tracking method, was applied to determine time-resolved and three-dimensional flow velocities

In this study, a two-dimensional shallow-water-equation numerical model is developed for simulating free surface water flows with internal moving wet/dry front boundaries. It is based on the Eulerian aspect and meshless approach. The predictor-corrector process is used for the time marching. The spatial derivatives of physical quantities are computed using the local polynomial approximation with the

ABSTRACT An experimental analysis of the dynamics of avalanches for different stages of development and turbulent flow conditions is introduced. Experiments were conducted in a laboratory flume using clear-water conditions and a video camera placed within an acrylic cylinder. The results of a proper orthogonal decomposition of the pre-processed image sequences highlighted the existence of two types

To reduce local scour around bridge piers, a mitigation measure requiring a submerged triangular flow diversion structure is proposed. Different dimensions, locations, and submergence ratios were examined experimentally. Using Taguchi’s method to minimize the number of alternative tests, 27 alternative tests were undertaken to ascertain the optimum size and location for the structure. Compared to the

ABSTRACT Aquatic vegetation is an important component of coastal and riverine environments and plays a significant role in shaping their evolution. The extent and nature of eco-hydraulic interaction depends upon the geometric and biophysical properties of the vegetation which affect the drag force and vegetation reconfiguration. Such vegetation properties commonly vary along each stem. However, this

Erosion of sediments is of crucial significance to morphologic evolution, management of water quality and aquatic ecosystems. However, the prediction of the pickup rate of non-cohesive sediments is a challenging topic because of the complex interaction between the bed and the flow. This study reports the experimental results of the pickup rate of non-cohesive sediments in uniform flows. Six groups

One of the most used 1D tools to model collection systems is the Storm Water Management Model (SWMM). Solving the full form of the Saint Venant equations, this model represents typical unsteady flow conditions in sewer systems. However, it may be insufficient to address fast transient flow conditions that can be present during extreme events or unscheduled operational conditions. SWMM version 5.1.013

A series of lock-release experiments are carried out to investigate the hydrodynamics of weakly and strongly stratified two-layer gravity currents (GC) on a flat bottom. A particle image velocimetry (PIV) system combined with an optical method is used to obtain the mixing process, front velocity, and velocity profiles of the two-layer GCs, focusing on the effect of the initial height ratio and lock

ABSTRACT In the proposed work, a numerical model of the water flow during dam breakthrough using the volume of fluid (VOF) method is constructed. The mathematical model consists of a system of Navier–Stokes equations, and also includes equations for the phase and motion of particles. For the simulation, the SST k−ω turbulent model was used. To solve the system of equations, the PISO algorithm was used

The turbulent plunging jet of a nearly incompressible fluid into a stagnant fluid is of great importance in many practical applications, especially for the engineering of hydropower. As an example, the dynamic load exerted by the impact of turbulent high-velocity jets into a pool must be estimated to evaluate the potential destabilization of a rock bed or dam’s structure. Modelling plunging jets in

This paper presents both experimental measurements and three-dimensional (3D) numerical simulations of turbulent flow in open channels with simulated partial ice-covers. The experiments were conducted with a particle image velocimetry system while the simulations were performed with five eddy-viscosity and second-moment closure turbulence models. Four coverage ratios based on the channel width were

A well-balanced and positivity-preserving meshless method based on smoothed particle hydrodynamics (SPH) is developed to simulate one-dimensional (1D) and two-dimensional (2D) shallow water (SW) flows in open channels with irregular geometries. A new form of the characteristic equations that govern the water-surface level and water velocity is introduced to specify the numerical inflow/outflow boundary

(2021). Comparison between hydrostatic and total pressure simulations of dam-break flows By LEONARDO R. MONTEIRO, LUÍSA V. LUCCHESE and EDITH B. C. SCHETTINI, J. Hydraulic Res. 58(5), 725–737. Journal of Hydraulic Research: Vol. 59, No. 2, pp. 351-354.

(2021). Closure to “Comparison between hydrostatic and total pressure simulations of dam-break flows” by LEONARDO R. MONTEIRO, LUÍSA V. LUCCHESE and EDITH B. C. SCHETTINI, J. Hydraulic Res., 58(5), 725–737. https://doi.org/10.1080/00221686.2019.167150. Journal of Hydraulic Research: Vol. 59, No. 2, pp. 354-354.

(2021). Correction. Journal of Hydraulic Research: Vol. 59, No. 2, pp. ciii-ciii.

Over the last two decades, interest in the free-surface behaviour of gravity-driven shallow turbulent flows has increased considerably. It is believed that observation of free-surface behaviour can provide useful information about the hydrodynamic characteristics of the flow and enable remote retrieval of these characteristics to non-invasively and rapidly monitor river flows. At the current state

Hydraulic structures are man-made waterworks interacting with the rainfall run-off to store and convey water, or mitigate the impact of run-off. Current approaches in hydraulic structure design tend to be conservative, not much differing from ancient designs. Modern structures are often designed based upon simplistic concepts to optimize their performances. However, today’s hydraulic engineers must

(2021). A Lagrangian drifter for surveys of water surface roughness in streams By CHRISTIAN NOSS, KAAN KOCA, PEGGY ZINKE, PIERRE-YVES HENRY, CHRISTY USHANTH NAVARATNAM, JOCHEN ABERLE and ANDREAS LORKE, J. Hydraulic Res. 58(3), 471–488. https://doi.org/10.1080/00221686.2019.1623930. Journal of Hydraulic Research: Vol. 59, No. 1, pp. 176-178.

(2021). Closure to “A Lagrangian drifter for surveys of water surface roughness in streams” by CHRISTIAN NOSS, KAAN KOCA, PEGGY ZINKE, PIERRE-YVES HENRY, CHRISTY USHANTH NAVARATNAM, JOCHEN ABERLE and ANDREAS LORKE, J. Hydraulic Res. Journal of Hydraulic Research: Vol. 59, No. 1, pp. 178-179.

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