scholarly journals Numerical evaluation of discharge coefficient and energy dissipation of flow over a stepped morning glory spillway

2021 ◽  
Vol 9 (2) ◽  
Author(s):  
Mohammad Alkhamis ◽  
◽  
Saeed Reza Sabbagh-Yazdi ◽  
Mohsen Ranjbar-Malekshah ◽  
◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Water Flow ◽  
Unit Length ◽  
Morning Glory ◽  
Design Parameters ◽  
Stepped Spillway ◽  
Reservoir Water ◽  
Flow Solver ◽  
Hydraulic Design ◽  
Coefficient Of Discharge

A morning glory spillway usually has an ogee shaped crest and conveys spill water flow to its downstream vertical shaft followed by a horizontal tunnel. The ungated morning glory spillways should convey variable discharges, which nonlinearly depends on the reservoir water elevation. The variation of discharge for unit length of the crest may cause challenges on design of downstream crest curve (which affects coefficient of discharge and downstream crest negative pressure). Furthermore, formation of a horizontal vortex flow affects the spillway discharge. In this paper, in order to resolve these problems by energy dissipation and water flow aeration, variable size steps are mapped to downstream of the curved ogee crest of morning glory spillway. A finite volume base numerical flow solver is used to investigate the effects of the considered configurations on the hydraulic design parameters. In this work, having verified the pressure and aeration of the flow over an ordinary stepped spillway, the characteristics of flow over geometry of an ordinary morning glory spillway, as well as stepped spillway, are modelled and compared to the available measurements on laboratory hydraulic models. Finally, an existing ordinary morning glory spillway is computationally modelled by considering an alternative design of variable sized steps at downstream crest (by mapping their edges to the ordinary profile of the morning glory spillway). The stepped morning glory spillway alternatives are numerically simulated for various flow rates, and the computed discharge coefficients and energy dissipations are compared with simulation results for ordinary morning glory spillway of the case.

scholarly journals Uniform flow and energy dissipation of hydraulic-jump-stepped spillways

2020 ◽  
Vol 20 (4) ◽  
pp. 1546-1553
Author(s):  
Yu Zhou ◽  
Jianhua Wu ◽  
Fei Ma ◽  
Jianyong Hu
Keyword(s):  
Energy Dissipation ◽  
Water Flow ◽  
Hydraulic Jump ◽  
Flow Region ◽  
Uniform Flow ◽  
Stepped Spillway ◽  
Flow Depth ◽  
Clear Water ◽  
Air Concentration ◽  
Stepped Spillways

Abstract In skimming flow, a uniform flow can be achieved and the flow depth, velocity and air concentration remain constant if a stepped spillway is sufficiently long. In this study, physical model experiments were performed to investigate the uniform characteristics and energy dissipation of a hydraulic-jump-stepped spillway, which is a new type of stepped spillway for increasing the unit discharge capacity and energy dissipation. Based on the redefinition of uniform flow, experimental results show that at a given stepped spillway slope, a smaller height for the beginning of the uniform flow region, a greater uniform aerated flow depth and a greater uniform equivalent clear water flow depth can be obtained as compared with the traditional stepped spillway due to strong aeration in the aeration basin. Under the condition of uniform flow, the energy dissipation rate of stepped spillways can be estimated by the equivalent clear water flow depth with given inflow conditions. Compared with the traditional stepped spillway, the uniform flow over the hydraulic-jump-stepped spillway has a smaller specific energy, revealing that the hydraulic-jump-stepped spillway is more advantageous for dissipating energy, especially at large unit discharges.

scholarly journals Numerical Simulation of Stepped Spillways with Front Step Deformation

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Guodong Li ◽  
Haifeng Zhang ◽  
Xingnan Li ◽  
Lihao Guo ◽  
Yanyan Gao ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Water Flow ◽  
Dissipation Rate ◽  
Energy Dissipation Rate ◽  
Maximum Energy ◽  
Single Step ◽  
Stepped Spillway ◽  
Flow State ◽  
Front Step

In order to solve the flood discharge problem of both small- and medium-sized warping dams in the Loess Plateau, a stepped spillway scheme, based on an ecological bag, to achieve full-section water flow and energy dissipation has been proposed in this paper. The hydraulic and energy dissipation characteristics of a stepped spillway layout scheme were studied using 3D numerical simulation. As the height of the dams is low and the spillways are short, the research has shown that the traditional single-step layout scheme leads to a low overall energy dissipation rate due to the small amount of energy dissipated in the initial steps. As a result of this, this paper has put forward two kinds of step layout schemes such as the shunt type and the staggered type for the initial steps. Through analysis of the flow state, the pressure distribution, and the total energy dissipation rate, the results have shown that shunt type and staggered type with front step deformation produced an obvious mixing of the water flow, fewer negative pressure areas, and a higher energy dissipation rate. The optimal energy dissipation rate of the staggered type reached 87.75%, and the maximum energy dissipation rate was increased by 27.97%.

scholarly journals ONE- AND THREE-DIMENSIONAL MODELING OF A VERTICAL-SLOT FISHWAY

2017 ◽  
pp. 99-107 ◽  
Author(s):  
Camila Yuri Lira Umeda ◽  
Guilherme de Lima ◽  
Johannes Gérson Janzen ◽  
Marcio Ricardo Salla
Keyword(s):  
Energy Dissipation ◽  
Dissipation Rate ◽  
Numerical Models ◽  
Three Dimensional ◽  
Energy Dissipation Rate ◽  
Flow Speed ◽  
Design Parameters ◽  
Vertical Slot ◽  
Hydraulic Design ◽  
Vertical Slot Fishway

This paper compares the use of one-dimensional (1-D) and three-dimensional (3-D) numerical models to simulate the flow of a vertical-slot fishway. Prior to their application, the models are validated by comparing the predicted data with experimental data from a physical model. Then the numerical models are applied to calculate four critical hydraulic design parameters of vertical-slot fishways, i.e., flow speed, water depth, turbulent kinetic energy, and energy dissipation rate. Furthermore, the authors developed rating curves for flow rate and energy dissipation rate in terms of flow depth using data from the 1-D model. These curves have great utility for the operation of the vertical-slot fishway studied. The results indicate that 1-D modeling can be a useful tool for preliminary conservative design arrangements of vertical-slot fishways, and that 3-D modeling can be a useful tool to enable accurate representation of the critical hydraulic design parameters and selection of the most appropriate design.

scholarly journals Turbulence characteristics in skimming flows on stepped spillways

2008 ◽  
Vol 35 (9) ◽  
pp. 865-880 ◽  
Author(s):  
G. Carosi ◽  
H. Chanson
Keyword(s):  
Energy Dissipation ◽  
Water Flow ◽  
Time Scales ◽  
Bubbly Flow ◽  
Stepped Spillway ◽  
Phase Detection ◽  
Flow Properties ◽  
Flow Measurements ◽  
Stepped Spillways ◽  
Turbulent Characteristics

The stepped spillway design is characterized by an increase in the rate of energy dissipation on the chute associated with a reduction of the size of the downstream energy dissipation system. This study presents a thorough investigation of the air–water flow properties in skimming flows with a focus on the turbulent characteristics. New measurements were conducted in a large-size facility (θ = 22°; step height, h = 0.1 m) with several phase-detection intrusive probes. Correlation analyses were applied to estimate the integral turbulent length and time scales. The skimming flow properties presented some basic characteristics that were qualitatively and quantitatively in agreement with previous air–water flow measurements in skimming flows. Present measurements showed some relatively good correlation between turbulence intensities T u and turbulent length and time scales. These measurements also illustrated large turbulence levels and large turbulent time and length scales in the intermediate region between the spray and bubbly flow regions.

Automated simulation techniques for uncovering high-performance bioinspired cellular structures under blast loads

2021 ◽  
pp. 109963622110204
Author(s):  
Abdallah Ghazlan ◽  
Tuan Ngo ◽  
Tay Son Le ◽  
Tu Van Le
Keyword(s):  
Energy Dissipation ◽  
Trabecular Bone ◽  
Reaction Force ◽  
Blast Loading ◽  
Performance Criteria ◽  
Superior Performance ◽  
Cellular Structures ◽  
Design Parameters ◽  
Engineering Practice ◽  
Automated Simulation

Trabecular bone possesses a complex hierarchical structure of plate- and strut-like elements, which is analogous to structural systems encountered in engineering practice. In this work, key structural features of trabecular bone are mimicked to uncover effective energy dissipation mechanisms under blast loading. To this end, several key design parameters were identified to develop a bone-like unit cell. A computer script was then developed to automatically generate bone-like finite element models with many combinations of these design parameters, which were simulated under blast loading. The optimal structure was identified and its performance was benchmarked against traditional engineered cellular structures, including those with hexagonal, re-entrant and square cellular geometries. The bone-like structure showed superior performance over its engineered counterparts using the peak transmitted reaction force and energy dissipation as the key performance criteria.

Estimation of Seismic Energy Dissipation for Steel Slit Shear Walls Considering Out-of-Plane Buckling

2021 ◽  
Author(s):  
Yiming Ma ◽  
Liusheng He ◽  
Ming Li
Keyword(s):  
Energy Dissipation ◽  
Shear Walls ◽  
Seismic Energy ◽  
Thickness Ratio ◽  
Design Parameters ◽  
Test Results ◽  
Loading Test ◽  
Aspect Ratios ◽  
Out Of Plane ◽  
Energy Dissipation Capacity

Steel slit shear walls (SSSWs), made by cutting slits in steel plates, are increasingly adopted in seismic design of buildings for energy dissipation. This paper estimates the seismic energy dissipation capacity of SSSWs considering out-of-plane buckling. In the experimental study, three SSSW specimens were designed with different width-thickness ratios and aspect ratios and tested under quasi-static cyclic loading. Test results showed that the width-thickness ratio of the links dominated the occurrence of out-of-plane buckling, which produced pinching in the hysteresis and thus reduced the energy dissipation capacity. Out-of-plane buckling occurred earlier for the links with a larger width-thickness ratio, and vice versa. Refined finite element model was built for the SSSW specimens, and validated by the test results. The concept of average pinching parameter was proposed to quantify the degree of pinching in the hysteresis. Through the parametric analysis, an equation was derived to estimate the average pinching parameter of the SSSWs with different design parameters. A new method for estimating the energy dissipation of the SSSWs considering out-of-plane buckling was proposed, by which the predicted energy dissipation agreed well with the test results.

scholarly journals ARPEC: A NOVEL STAGGERED PERFORATED CAISSON FOR WAVE ABSORPTION AND TIDAL FLUSHING

2020 ◽  
pp. 26
Author(s):  
Paolo Sammarco ◽  
Leopoldo Franco ◽  
Giorgio Bellotti ◽  
Claudia Cecioni ◽  
Stefano DeFinis
Keyword(s):  
Energy Dissipation ◽  
Water Flow ◽  
Wave Energy ◽  
Reflection And Transmission ◽  
Wave Energy Dissipation ◽  
Wave Absorption ◽  
Transmission Coefficients ◽  
Open Sea ◽  
Caisson Breakwater ◽  
Perforated Caisson

An innovative caisson breakwater geometry (patent pending) named "ARPEC" (Anti Reflective PErmeable Caisson) includes openings at all external and internal walls and at lateral (cross) ones, yet in a staggered pattern, to provide a labyrinthian hydraulic communication between the open sea and the internal waters. The complex sinuous water-flow within the consecutive permeable chambers thus favors wave energy dissipation as well as port water flushing and quality, with very low reflection and transmission coefficients. 2D lab model tests demonstrate the system effectiveness.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/PaUsinYO-Zo

scholarly journals Energy Dissipation in Solid Roller Bucket and Controlled Stilling Basin for Ogee Stepped Spillway

2019 ◽  
Vol 8 (4) ◽  
pp. 2109-2112
Keyword(s):  
Energy Dissipation ◽  
Laboratory Experiments ◽  
Ideal Condition ◽  
Stepped Spillway ◽  
Type Ii ◽  
Dimensional Parameter ◽  
Stilling Basin ◽  
Sequent Depth ◽  
Tail Water ◽  
The Ideal

Hydraulic jump type II stilling basin is generally preferred as an energy dissipator for ogee spillway but it is uneconomical due to longer structure. On the other hand, roller bucket uses relatively shorter structure over a sloping apron or horizontal stilling basin. In this study, an attempt has been made to evaluate the performance of an ogee profile stepped spillway in combination with solid roller bucket and stilling basin type II for energy dissipation. Laboratory experiments are performed on a physical working model of ogee profile stepped spillway at discharge ranging from 0.0032 to 0.0069 m3 /s for a head of 1.5m, 4m & 7m and the results compared for energy dissipation (non-dimensional parameter (y c / h) = 0.69). The model results show that stepped spillway model without v-notch achieves 92.40 % energy dissipation. Thus this model is found to be more suitable to acquire the ideal condition of sequent depth and tail water depth in stilling basin for all the discharges.

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