scholarly journals Apron and Cutoff Wall Scour Protection for Piano Key Weirs

Water ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2332
Author(s):  
Wyatt Lantz ◽  
Brian Mark Crookston ◽  
Michele Palermo
Keyword(s):  
Large Scale ◽  
Open Channel ◽  
Control Structure ◽  
Cutoff Wall ◽  
Specific Design ◽  
Experimental Campaign ◽  
Hydraulic Conditions ◽  
Weir Height ◽  
Scour Protection ◽  
Design Guidance

Piano key (PK) weirs are used in a variety of flow control structure applications, including spillway crests and open channel diversion structures. However, to the best of authors’ knowledge, structure-specific design guidance for scour mitigation is still needed. To fill this gap of knowledge, a systematic experimental campaign was conducted by testing different configurations of horizontal aprons with a cutoff wall. Protection structures were located at the toe of the PK weir. Namely, experiments were performed at large-scale to assess the effect of three apron lengths on downstream scour hole geometry under different hydraulic conditions. It was observed that a horizontal apron deflects the plunging jets originating from the PK weir, thus significantly reducing scour. Experimental evidence allowed corroboration that significant scour depth reduction occurs for an apron length 1.5 times the weir height, with longer aprons found to provide marginal benefits. Finally, also provided herein are tools to estimate the main scour characteristics and help practitioners in optimizing apron design.

Analytical and Computational Analysis of Turbulent Bouyant Jets in the Containment Atmosphere

2008 ◽  
Author(s):  
Enrico Deri ◽  
Matteo Bucci ◽  
Etienne Studer ◽  
Daniele Abdo
Keyword(s):  
Large Scale ◽  
Computational Analysis ◽  
Severe Accident ◽  
Buoyant Jets ◽  
Computational Tools ◽  
Experimental Campaign ◽  
Hydraulic Conditions ◽  
Computer Codes ◽  
Computational Fluid Dynamics Cfd

In case of severe accident, complex thermal-hydraulics phenomena are expected to occur in the containment atmosphere. To investigate and understand these phenomena, fundamental for nuclear safety and design, major efforts are being spent all over the world. A new OECD project, named SETH-2, is conceived to generate relevant experimental data, useful to improve the modeling capabilities of the computer codes aimed to predict post-accident containment thermal-hydraulic conditions. The Commissariat a` l’Energie Atomique (CEA) contributes to the project performing experiments within the large scale MISTRA facility. Tests are proposed to investigate mixing phenomena promoted in a stratified containment. In particular, one of these test series concerns the interaction of buoyant jets with a stratified atmosphere. The present work is aimed to develop and validate computational tools useful to support the design of this experimental campaign and to analyze the actual MISTRA tests. In this aim, two different models have been implemented for turbulent buoyant jets in a stratified atmosphere: an engineering analytical model for a fast characterization of flow structures and a finite elements computational fluid dynamics (CFD) model that allows a detailed analysis of local phenomena. The models have been successfully validated for vertical buoyant jets in uniform atmosphere. Further experimental and numerical activities are illustrated, aimed to carry out the validation with stratified atmosphere and inclined injections.

Seeding metrics for image velocimetry performances in rivers

2021 ◽  
Author(s):  
Silvano Fortunato Dal Sasso ◽  
Alonso Pizarro ◽  
Sophie Pearce ◽  
Ian Maddock ◽  
Matthew T. Perks ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Optical Sensors ◽  
Large Scale ◽  
Surface Flow ◽  
Surface Velocity ◽  
Seeding Density ◽  
Earth System ◽  
Science Data ◽  
Image Velocimetry ◽  
Hydraulic Conditions

<p>Optical sensors coupled with image velocimetry techniques are becoming popular for river monitoring applications. In this context, new opportunities and challenges are growing for the research community aimed to: i) define standardized practices and methodologies; and ii) overcome some recognized uncertainty at the field scale. At this regard, the accuracy of image velocimetry techniques strongly depends on the occurrence and distribution of visible features on the water surface in consecutive frames. In a natural environment, the amount, spatial distribution and visibility of natural features on river surface are continuously challenging because of environmental factors and hydraulic conditions. The dimensionless seeding distribution index (SDI), recently introduced by Pizarro et al., 2020a,b and Dal Sasso et al., 2020, represents a metric based on seeding density and spatial distribution of tracers for identifying the best frame window (FW) during video footage. In this work, a methodology based on the SDI index was applied to different study cases with the Large Scale Particle Image Velocimetry (LSPIV) technique. Videos adopted are taken from the repository recently created by the COST Action Harmonious, which includes 13 case study across Europe and beyond for image velocimetry applications (Perks et al., 2020). The optimal frame window selection is based on two criteria: i) the maximization of the number of frames and ii) the minimization of SDI index. This methodology allowed an error reduction between 20 and 39% respect to the entire video configuration. This novel idea appears suitable for performing image velocimetry in natural settings where environmental and hydraulic conditions are extremely challenging and particularly useful for real-time observations from fixed river-gauged stations where an extended number of frames are usually recorded and analyzed.</p><p> </p><p><strong>References </strong></p><p>Dal Sasso S.F., Pizarro A., Manfreda S., Metrics for the Quantification of Seeding Characteristics to Enhance Image Velocimetry Performance in Rivers. Remote Sensing, 12, 1789 (doi: 10.3390/rs12111789), 2020.</p><p>Perks M. T., Dal Sasso S. F., Hauet A., Jamieson E., Le Coz J., Pearce S., …Manfreda S, Towards harmonisation of image velocimetry techniques for river surface velocity observations. Earth System Science Data, https://doi.org/10.5194/essd-12-1545-2020, 12(3), 1545 – 1559, 2020.</p><p>Pizarro A., Dal Sasso S.F., Manfreda S., Refining image-velocimetry performances for streamflow monitoring: Seeding metrics to errors minimisation, Hydrological Processes, (doi: 10.1002/hyp.13919), 1-9, 2020.</p><p>Pizarro A., Dal Sasso S.F., Perks M. and Manfreda S., Identifying the optimal spatial distribution of tracers for optical sensing of stream surface flow, Hydrology and Earth System Sciences, 24, 5173–5185, (10.5194/hess-24-5173-2020), 2020.</p>

A Method for Classifying Products Designed for the Developing World

2016 ◽  
Author(s):  
Paden M. Troxell ◽  
Charles Kim
Keyword(s):  
Developing World ◽  
Design Principles ◽  
Product Class ◽  
Specific Design ◽  
Step Method ◽  
Specific Product ◽  
Potential Value ◽  
Design Characteristics ◽  
Design Guidance

Researchers in the area of design for the developing world have synthesized knowledge from location-specific product case studies in the form of design guidance, which includes pitfalls, principles, and methods. Much of the design guidance relates to specific product classes and regions, while recent work is directed towards generalized principles. The aim of this paper is to fill gaps in product class-specific design guidance by creating larger groups of similar products, which share design characteristics. In this paper, we present a method for classifying products into such groups utilizing cluster analysis. We present a five-step method, which includes optional synthesis of design principles. The potential value of the method is demonstrated in a case study. The result included two distinct product groups, titled Products for Relief and Products for Development, and corresponding design principles for each group.

scholarly journals Automated Detection of Instability-Inducing Channel Geometry Transitions in Saint-Venant Simulation of Large-Scale River Networks

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2236
Author(s):  
Cheng-Wei Yu ◽  
Ben R. Hodges ◽  
Frank Liu
Keyword(s):  
Large Scale ◽  
Open Channel ◽  
Search Algorithm ◽  
Shallow Water Equation ◽  
Stable Solution ◽  
River Networks ◽  
River Systems ◽  
Channel Network ◽  
Channel Geometry ◽  
Venant Equation

A new sweep-search algorithm (SSA) is developed and tested to identify the channel geometry transitions responsible for numerical convergence failure in a Saint-Venant equation (SVE) simulation of a large-scale open-channel network. Numerical instabilities are known to occur at “sharp” transitions in discrete geometry, but the identification of problem locations has been a matter of modeler’s art and a roadblock to implementing large-scale SVE simulations. The new method implements techniques from graph theory applied to a steady-state 1D shallow-water equation solver to recursively examine the numerical stability of each flowpath through the channel network. The SSA is validated with a short river reach and tested by the simulation of ten complete river systems of the Texas–Gulf Coast region by using the extreme hydrological conditions recorded during hurricane Harvey. The SSA successfully identified the problematic channel sections in all tested river systems. Subsequent modification of the problem sections allowed stable solution by an unsteady SVE numerical solver. The new SSA approach permits automated and consistent identification of problem channel geometry in large open-channel network data sets, which is necessary to effectively apply the fully dynamic Saint-Venant equations to large-scale river networks or for city-wide stormwater networks.

scholarly journals Causes and consequences of long-term groundwater overabstraction in Jordan

2021 ◽  
Author(s):  
Florian Brückner ◽  
Rebecca Bahls ◽  
Mohammad Alqadi ◽  
Falk Lindenmaier ◽  
Ibraheem Hamdan ◽  
...  
Keyword(s):  
Water Supply ◽  
Large Scale ◽  
Flow Direction ◽  
Groundwater Resources ◽  
Regional Scale ◽  
Irrigated Agriculture ◽  
Groundwater Levels ◽  
Contour Lines ◽  
Hydraulic Conditions ◽  
Groundwater Basins

AbstractIn 2017, a comprehensive review of groundwater resources in Jordan was carried out for the first time since 1995. The change in groundwater levels between 1995 and 2017 was found to be dramatic: large declines have been recorded all over the country, reaching more than 100 m in some areas. The most affected areas are those with large-scale groundwater-irrigated agriculture, but areas that are only used for public water supply are also affected. The decrease of groundwater levels and saturated thickness poses a growing threat for drinking water supply and the demand has to be met from increasingly deeper and more remote sources, causing higher costs for drilling and extraction. Groundwater-level contour lines show that groundwater flow direction has completely reversed in some parts of the main aquifer. Consequently, previously established conceptual models, such as the concept of 12 “groundwater basins” often used in Jordan should be revised or replaced. Additionally, hydraulic conditions are changing from confined to unconfined; this is most likely a major driver for geogenic pollution with heavy metals through leakage from the overlying bituminous aquitard. Three exemplary case studies are presented to illustrate and discuss the main causes for the decline of the water tables (agriculture and population growth) and to show how the results of this assessment can be used on a regional scale.

New Developments in Complete Nitrogen Removal with Biological Aerated Filters

1990 ◽  
Vol 22 (1-2) ◽  
pp. 273-280 ◽  
Author(s):  
Frank Rogalla ◽  
Marie-Marguerite Bourbigot
Keyword(s):  
Large Scale ◽  
Ammonia Oxidation ◽  
Bacterial Degradation ◽  
Operational Parameters ◽  
Design Data ◽  
New Developments ◽  
Hydraulic Conditions ◽  
Solids Retention ◽  
Extensive Pilot ◽  
Pilot Tests

Biological aerated filters combine bacterial degradation of pollution by fixed biomass with physical filtration in a single reactor.Several full-size plants with the BIOCARBONE process have established the compactness, ease of operation and high removal rates achievable with this advanced treatment system. Based on large-scale industrial experiences, a new biofilter design offering simplified operation and increased performance is presented. Design data for carbon and nutrient removal were collected during extensive pilot tests. Hydraulic conditions and pollution loadings were varied in order to optimize the biological and operational parameters of the filter. Carbon and ammonia oxidation as well as denitrification and suspended solids retention could be achieved with an overall hydraulic retention time of two hours.

scholarly journals Experimental Optimization of Gate-Opening Modes to Minimize Near-Field Vibrations in Hydropower Stations

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1435 ◽  
Author(s):  
Yong Peng ◽  
Jianmin Zhang ◽  
Weilin Xu ◽  
Matteo Rubinato
Keyword(s):  
Large Scale ◽  
Near Field ◽  
Detailed Comparison ◽  
Case Scenario ◽  
Gate Opening ◽  
Submerged Jets ◽  
Hydraulic Conditions ◽  
Opening Mode ◽  
Side Walls ◽  
Hydropower Stations

Multi-Horizontal-Submerged Jets are successfully applied to dissipate energy within a large-scale hydropower station. However, notable near-field vibrations are generated when releasing high discharges through the gates, which is generally typical in a flooding case scenario. Under these conditions, the magnitude of the vibrations varies when applying different gate-opening modes. To investigate and find optimized gate-opening modes to reduce the near-field vibration, multiple combinations were tested by varying gate-opening modes and hydraulic conditions. For each of the tests conducted, fluctuating pressures acting on side-walls and bottoms of a stilling basin were measured. The collected datasets were used to determine the maximum and minimum fluctuating pressure values associated with the correspondent gate-opening mode and a detailed comparison between each of the gate-opening modes was completed. The paper presents the quantitative analysis of the discharge ratio’s effect on fluctuating pressures. It also investigates the influence of different gate-opening modes by including side to middle spillways and upper to lower spillways configurations. The flow pattern evolutions triggered by each different gate-opening mode are discussed and optimal configurations that minimize near-field vibrations at high discharges are recommended to support both the design of new systems and assessment of the performance of existing ones.

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