scholarly journals Experimental study on the hydraulic capacity of grate inlets with supercritical surface flow conditions

2019 ◽  
Vol 79 (9) ◽  
pp. 1717-1726 ◽  
Author(s):  
Svenja Kemper ◽  
Andreas Schlenkhoff
Keyword(s):  
Numerical Models ◽  
Surface Flow ◽  
Physical Model Test ◽  
Geometrical Parameters ◽  
Flow Conditions ◽  
Rainfall Events ◽  
Real Flow ◽  
Underground System ◽  
Heavy Rainfall Events ◽  
Good Agreement

Abstract Due to an increasing number of heavy rainfall events, the managing of urban flooding requires new design approaches in urban drainage engineering. With bidirectional coupled numerical models the surface runoff, the underground sewer flow and the interaction processes between both systems can be calculated. Most of the numerical models use a weir equation to calculate the surface to sewer flow with unsurcharged flow conditions, but uncertainties still exist in the representation of the real flow conditions. Street inlets, existing in different types, are the connecting elements between the surface and the underground system. In the present study, an empirical formula was developed based on physical model test runs to estimate the hydraulic capacity and type-specific efficiency of grate inlets with supercritical surface flow. Influencing hydraulic parameters are water depth and flow velocity upstream of the grate and, in addition, different geometrical parameters are taken into account, such as the grate dimensions or the orientation of the bars (transverse, longitudinal or diagonal). Good agreement between estimated and measured results could be proven with relative deviations less than 1%.

Hydraulic Model and Numerical Simulation Study of Shuangwangcheng Pump Station

2011 ◽  
Vol 117-119 ◽  
pp. 647-651
Author(s):  
Chuan Qi Li ◽  
Wei Wang ◽  
Jie Gong ◽  
Xin Lai Zhao
Keyword(s):  
Numerical Simulation ◽  
Physical Model ◽  
Model Test ◽  
Hydraulic Model ◽  
Physical Model Test ◽  
Flow Conditions ◽  
Scheme Design ◽  
Model Studies ◽  
Pump Station ◽  
Good Agreement

Physical and numerical model studies were performed in order to study the flow conditions for the proposed pump station of Shuangwangcheng reservoir, Shouguang Ctiy. The flow velocity and the pressure distribution in the bidirectional culvert of Shuangwangcheng Pump Station had been obtained by hydraulic model test and numerical simulation. The physical model was constructed to a Froude scale of 1:20. A general conclusion was that, the computed results were good agreement with the data measured in physical model, and could be good complement for physical model test. Furthermore, negative pressure existing in discharge steep culvert in the initial scheme design was eliminated by moving the culvert controlling gate to the end of culvert in the modified scheme, and the flow conditions was improved.

scholarly journals Surface to sewer flow exchange through circular inlets during urban flood conditions

2018 ◽  
Vol 20 (3) ◽  
pp. 564-576 ◽  
Author(s):  
Matteo Rubinato ◽  
Seungsoo Lee ◽  
Ricardo Martins ◽  
James D. Shucksmith
Keyword(s):  
Steady State ◽  
Surface Flow ◽  
Scale Model ◽  
Geometrical Parameters ◽  
Flow Conditions ◽  
Urban Flood ◽  
Flood Modelling ◽  
Physical Scale ◽  
Hydraulic Conditions ◽  
Flow Through

Abstract Accurately quantifying the capacity of sewer inlets (such as manhole lids and gullies) to transfer water is important for many hydraulic flood modelling tools. The large range of inlet types and grate designs used in practice makes the representation of flow through and around such inlets challenging. This study uses a physical scale model to quantify flow conditions through a circular inlet during shallow steady state surface flow conditions. Ten different inlet grate designs have been tested over a range of surface flow depths. The resulting datasets have been used (i) to quantify weir and orifice discharge coefficients for commonly used flood modelling surface–sewer linking equations and (ii) to validate a 2D finite difference model in terms of simulated water depths around the inlet. Calibrated weir and orifice coefficients were observed to be in the range 0.115–0.372 and 0.349–2.038, respectively, and a relationship with grate geometrical parameters was observed. The results show an agreement between experimentally observed and numerically modelled flow depths but with larger discrepancies at higher flow exchange rates. Despite some discrepancies, the results provide improved confidence regarding the reliability of the numerical method to model surface to sewer flow under steady state hydraulic conditions.

Ability of Preissmann slot scheme to simulate smooth pressurisation transient in sewers

2010 ◽  
Vol 62 (8) ◽  
pp. 1848-1858 ◽  
Author(s):  
Giovanni Battista Ferreri ◽  
Gabriele Freni ◽  
Pietro Tomaselli
Keyword(s):  
Open Source Software ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Rainfall Events ◽  
Storm Water Management Model ◽  
Practical Applications ◽  
Software Products ◽  
Drainage Networks ◽  
Software Product ◽  
Heavy Rainfall Events

Urban drainage networks are generally designed to operate in a free-surface flow condition. However, as a consequence of heavy rainfall events or network malfunctions, the filling of sewers (pressurisation) and network overflow may occur. Several modelling software products are commonly used to simulate floods in drainage networks, and their results are usually thought to be reliable and robust. However, no specific studies have been carried out on the behaviour of these modelling products during the pressurisation transition. Mathematical models often use the Preissmann slot concept to handle pressurisation. In this paper, on the basis of laboratory pipe tests, the reliability of such a scheme is studied by means of a popular and open-source software product: SWMM (Storm Water Management Model). Many numerical tests were carried out with SWMM, varying the spatial and time steps and the Preissmann slot width, in order to examine the performance of the modelling software over intervals of these parameters even wider than what is usual in practical applications. The comparison between simulated and experimental surges allows one to draw interesting conclusions regarding the effectiveness of software products analogous to SWMM in simulating pressurisation, as well as the choice of the parameters themselves.

Modeling of mass transfer in biofilms in oscillatory flow conditions using k-ɛ turbulence model

2003 ◽  
Vol 3 (1-2) ◽  
pp. 201-207
Author(s):  
H. Nagaoka ◽  
T. Nakano ◽  
D. Akimoto
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Turbulence Model ◽  
Uptake Rate ◽  
Oscillatory Flow ◽  
Substrate Uptake ◽  
Flow Conditions ◽  
Mass Transfer Mechanism ◽  
Substrate Uptake Rate ◽  
Good Agreement

The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions. Numerical simulation of turbulence near a biofilm was conducted using the low Reynold’s number k-ɛ turbulence model. Substrate transfer in biofilms under oscillatory flow conditions was assumed to be carried out by turbulent diffusion caused by fluid movement and substrate concentration profile in biofilm was calculated. An experiment was carried out to measure velocity profile near a biofilm under oscillatory flow conditions and the influence of the turbulence on substrate uptake rate by the biofilm was also measured. Measured turbulence was in good agreement with the calculated one and the influence of the turbulence on the substrate uptake rate was well explained by the simulation.

scholarly journals Extreme Floods in the Eastern Part of Europe: Large-Scale Drivers and Associated Impacts

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1122
Author(s):  
Monica Ionita ◽  
Viorica Nagavciuc
Keyword(s):  
Water Vapor ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Flood Events ◽  
Rainfall Events ◽  
Catchment Areas ◽  
Large Scale Atmospheric Circulation ◽  
Heavy Rainfall Events

The role of the large-scale atmospheric circulation in producing heavy rainfall events and floods in the eastern part of Europe, with a special focus on the Siret and Prut catchment areas (Romania), is analyzed in this study. Moreover, a detailed analysis of the socio-economic impacts of the most extreme flood events (e.g., July 2008, June–July 2010, and June 2020) is given. Analysis of the largest flood events indicates that the flood peaks have been preceded up to 6 days in advance by intrusions of high Potential Vorticity (PV) anomalies toward the southeastern part of Europe, persistent cut-off lows over the analyzed region, and increased water vapor transport over the catchment areas of Siret and Prut Rivers. The vertically integrated water vapor transport prior to the flood peak exceeds 300 kg m−1 s−1, leading to heavy rainfall events. We also show that the implementation of the Flood Management Plan in Romania had positive results during the 2020 flood event compared with the other flood events, when the authorities took several precaution measurements that mitigated in a better way the socio-economic impact and risks of the flood event. The results presented in this study offer new insights regarding the importance of large-scale atmospheric circulation and water vapor transport as drivers of extreme flooding in the eastern part of Europe and could lead to a better flood forecast and flood risk management.

scholarly journals Optimization of the flow conditions in the spawning ground of the Chinese sturgeon (Acipenser sinensis) through Gezhouba Dam generating units

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anyang Huang ◽  
Jinzhong Yao ◽  
Jiazhi Zhu ◽  
Xingchen Gao ◽  
Wei Jiang
Keyword(s):  
Spawning Ground ◽  
Chinese Sturgeon ◽  
Flow Conditions ◽  
Velocity Measurements ◽  
Acipenser Sinensis ◽  
Critically Endangered Species ◽  
Gezhouba Dam ◽  
Opening Mode ◽  
Suitable Area ◽  
Good Agreement

AbstractChinese sturgeon (Acipenser sinensis) is a critically endangered species, and waters downstream from Gezhouba Dam are the only known spawning ground. To optimize the velocity conditions in the spawning ground by controlling the opening mode of Gezhouba Dam generator units, a mathematical model of Chinese sturgeon spawning ground was established in FLOW-3D. The model was evaluated with velocity measurements, and the results were determined to be in good agreement. By inverting the 2016–2019 field monitoring results, the model shows that the preferred velocity range for Chinese sturgeon spawning is 0.6–1.5 m/s. Velocity fields of different opening modes of the generator units were simulated with identical discharge. The suitable-velocity area was maximal when all units of Dajiang Plant of Gezhouba Dam were open. For discharges below 12,000 m3/s, most of the area was suitable; for discharges above 12,000 m3/s, the suitable area rapidly decreased with increasing discharge. A comparison of suitable areas under high-flow showed that at discharges of 12,000–15,000 m3/s, opening 11–13 units on the left side was optimal. For discharges above 15,000 m3/s, all units should be open. We used these results to recommend a new operation scheme to support the conservation of Chinese sturgeon.

Diabatic Nozzle Flow with Constant Small Stage Efficiency

1960 ◽  
Vol 64 (598) ◽  
pp. 632-635 ◽  
Author(s):  
R. A. A. Bryant
Keyword(s):  
Gas Flow ◽  
Nozzle Flow ◽  
Flow Conditions ◽  
One Dimensional ◽  
Real Flow ◽  
Stage Efficiency ◽  
Frictional Effects

The concept of small stage efficiency is introduced when studying one-dimensional gas flow in nozzles in order to permit a closer approximation of real flow conditions than is possible from an isentropic analysis. It is more or less conventional to assume the flow conditions are adiabatic whenever the small stage efficiency is used. That is to say, small stage efficiency is generally considered in relation to flows contained within adiabatic boundaries, in which case it becomes a measure of the heat generated by internal frictional effects alone.

A Streamline Curvature Method for Calculating S1 Stream Surface Flow

1984 ◽  
Vol 106 (2) ◽  
pp. 306-312
Author(s):  
S. K. Mao ◽  
D. T. Li
Keyword(s):  
Surface Flow ◽  
Approximation Technique ◽  
Flow Section ◽  
Boolean Expression ◽  
Simple Method ◽  
Stream Surface ◽  
Streamline Curvature ◽  
Calculation Results ◽  
Good Agreement ◽  
Streamline Curvature Method

A streamline curvature method for calculating S1 surface flow in turbines is presented. The authors propose a simple method in which a domain of calculation can be changed into an orderly rectangle without making coordinate transformations. Calculation results obtained on subsonic and transonic turbine cascades have been compared with those of experiment and another theory. Good agreement has been found. When calculating blade-to-blade flow velocity at subsonic speed, a function approximation technique can be used in lieu of iteration method in order to reduce calculation time. If the calculated flow section is of a mixed (subsonic-supersonic) flow type, a Boolean expression obtained from the truth table of flow states is proposed to judge the integrated character of the mixed flow section. Similarly, another Boolean expression is used to determine whether there exists a “choking” of the relevant section. Periodical conditions are satisfied by iterating the first-order derivative of stagnation streamline, which is formed simultaneously. It can be proved that the stagnation streamline formed in this way is unique.

A New Methodology for the Reliability Based Particle Swarm Optimization with Simulated Annealing

2011 ◽  
Vol 274 ◽  
pp. 101-111 ◽  
Author(s):  
Norelislam Elhami ◽  
Rachid Ellaia ◽  
Mhamed Itmi
Keyword(s):  
Particle Swarm Optimization ◽  
Simulated Annealing ◽  
Numerical Models ◽  
Limit State ◽  
Particle Swarm ◽  
Geometrical Parameters ◽  
Rectangular Plates ◽  
Swarm Optimization ◽  
Reliability Methods ◽  
State Functions

This paper presents a new methodology for the Reliability Based Particle Swarm Optimization with Simulated Annealing. The reliability analysis procedure couple traditional and modified first and second order reliability methods, in rectangular plates modelled by an Assumed Modes approach. Both reliability methods are applicable to the implicit limit state functions through numerical models, like those based on the Assumed Mode Method. For traditional reliability approaches, the algorithms FORM and SORM use a Newton-Raphson procedure for estimate design point. In modified approaches, the algorithms are based on heuristic optimization methods such as Particle Swarm Optimization and Simulated Annealing Optimization. Numerical applications in static, dynamic and stability problems are used to illustrate the applicability and effectiveness of proposed methodology. These examples consist in a rectangular plates subjected to in-plane external loads, material and geometrical parameters which are considered as random variables. The results show that the predicted reliability levels are accurate to evaluate simultaneously various implicit limit state functions with respect to static, dynamic and stability criterions.

scholarly journals An approach to the modeling of a virtual thermal manikin

2014 ◽  
Vol 18 (4) ◽  
pp. 1413-1423 ◽  
Author(s):  
Dragan Ruzic ◽  
Sinisa Bikic
Keyword(s):  
Turbulence Models ◽  
Thermal Conditions ◽  
Heat Fluxes ◽  
Thermal Manikin ◽  
Flow Conditions ◽  
Body Segments ◽  
Nominal Size ◽  
Natural Flow ◽  
Good Agreement ◽  
Made In

The aim of the research described in this paper, is to make a virtual thermal manikin that would be simple, but also robust and reliable. The virtual thermal manikin was made in order to investigate thermal conditions inside vehicle cabins. The main parameters of the presented numerical model that were investigated in this paper are mesh characteristics and turbulence models. Heat fluxes on the manikin's body segments obtained from the simulations were compared with published results, from three different experiments done on physical thermal manikins. The presented virtual thermal manikin, meshed with surface elements of 0.035 m in nominal size (around 13,600 surface elements) and in conjunction with the two-layer RANS Realizable k-? turbulence model, had generally good agreement with experimental data in both forced and natural flow conditions.

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