Pipe Network Model Research Articles

Multi-objective optimization of the management of a waterworks using an integrated well field model

This study uses multi-objective optimization of an integrated well field model to improve the management of a waterworks. The well field model, called WELLNES (WELL field Numerical Engine Shell) is a dynamic coupling of a groundwater model, a pipe network model, and a well model. WELLNES is capable of predicting the water level and the energy consumption of the individual production wells. The model has been applied to Søndersø waterworks in Denmark, where it predicts the energy consumption within 1.8% of the observed. The objectives of the optimization problem are to minimize the specific energy of the waterworks and to avoid inflow of contaminated water from a nearby contaminated site. The decision variables are the pump status (on/off), and the constraint is that the waterworks has to provide a certain amount of drinking water. The advantage of multi-objective optimization is that the Pareto curve provides the decision-makers with compromise solutions between the two competing objectives. In the test case the Pareto optimal solutions are compared with an exhaustive benchmark solution. It is shown that the energy consumption can be reduced by 4% by changing the pumping configuration without violating the protection against contamination.

On Steam Pipe Network Modeling and Flow Rate Calculation

The paper demonstrates the method to set up the pipe network hydraulic-thermal synthetic mode by applying hydraulic and thermal models of single pipe, and proposes the algorithm based on searching for the problem that iterative calculation sometimes cannot derive convergent reasonable result as well. Compared the calculated values with the measurements, it shows the validation of the model and effectiveness of the algorithm.

강우발생 시 해안지역 대장균 유출에 관한 연구

해안지역은 해수욕, 어패류의 수집 등의 각종 레크레이션에 있어 많은 사람들이 이용하는 공간이며, 해수는 해안지역에서 각종 활동 중 섭취할 가능성이 있으므로, 수질이 매우 중요하다고 할 수 있다. 이에 본 연구에서는 실제 해수욕장의 수치 모의(수리, 수문, 수질)를 통하여 우수 및 오수가 지표를 통해 해안으로 유입될 경우의 해안지역에서 수질의 영향에 관하여 연구하였다. 지표에서의 우수 유출 및 오수의 흐름 수치해석은 MOUSE 모델을 사용하였으며 해안지역의 수치해석은 MIKE 3 모델을 사용하였다. 또한 수질 분석을 위하여 대장균의 증감에 영향을 주는 해당 지역의 기온, 수온, 일조량 등의 각종 인자를 구성하여 MIKE 3의 ECOLAB 모듈을 통하여 생물학적 분석을 수행하였다. 그 결과, 해수의 오염이 발생하면, 해수욕이 가능한 기간을 위주로 확인하였을 시, 대장균이 해수에 존재하는 시간은 연간 총 200시간 가량인 것으로 나타났으며, 강우 시 해수의 오염이 발생하면 강우가 그친 뒤에도 대장균이 완전히 사멸할 때 까지 4~6시간의 정화기간이 필요한 것으로 나타났다. 그리고 첨두 오염 부하량은 비가 그친 직후에 나타나는 것으로 나타났으며 대장균의 해수 유입은 5 mm 이상의 강우일 경우에 기준치 이상의 대장균이 발생하고, 해당 지역에 합류식 하수관거가 있을 시에 더욱 많이 발생하는 것으로 나타났다. Coastal areas are excellent venues for tourism and recreational activities promoting health and therapeutic benefits for its users. Thus, needless to say, it is very important to ensure good water quality in these bathing areas to protect people's health. Various guidelines regarding beach water quality exist throughout the world. However, proper monitoring systems for efficient collection and analysis of water quality and up-to-date dissemination of information are yet to be widely implemented. In this study, bathing water quality modeling and analysis is performed through the conjunctive use of several powerful modeling softwares. MOUSE, a physically-based model, was used to represent a one-dimensional pipe network model simulating the hydrodynamic and water quality behavior of the urban drainage system of Gentofte, Denmark. MIKE 3 FM was also applied to simulate coastal hydraulics and bacterial advection.dispersion considering biological decay. For the simulated rain events, checking exceedance (where concentration is greater than 500 counts per 100 ml) in defined bathing points identified a maximum total duration of 58 hours in Bellevue beach. However, checking for the entire coastal area revealed a maximum exceedance duration of 212.5 hours. This indicates the importance of comprehensive determination of bathing water quality in the area.

Studies on the Integration of Geographic Information System (GIS) and Drainage Pipe Network Model

With the development of the simulative theory and calculation method of drainage pipe network, urban drainage pipe network model gradually become an indispensable part of the urban drainage system management. The characteristics of modern drainage pipelines,the content of drainage pipelines system model, the problems of combining GIS with drainage pipelines and how to solve them are briefly described in this paper.

Model of Complicate Pipe Network Computation of Building Smoke Control System

According to the deficiency of present complicate pipe network’s calculating methods in smoke control system, a calculation model of complicate pipe network in buildings smoke control system is established here based on the theory of ventilation network. Graph Theory is used to obtain the model of pipe network in a smoke control system, air leak branch is applied to deal with air leak channels between pressurization area and non-pressurization area in a positive pressure smoke control system, and the equivalent air resistance of air leak branch is also calculated. Based on the equations of nodes flow balance and loop pressure balance, the calculation model of complicate pipe network is built to obtain the distribution method of air flows in a pipe network. The concept of fixed flow branch is introduced here to compute the total pressure drop and airflow regulation parameters of a pipe network. The research work in this paper perfects the calculation methods of complicate pipe network in a building smoke control system.

STEADY STATE AND DYNAMIC MODELING OF AN INDIRECT DISTRICT HEATING SYSTEM

An indirect district heating system (IDHS) with heated floor area of 851 031 m2 and ten heat exchange stations was modeled in this study. An aggregated steady state model for the system was developed to study the impact of important system parameters. A dynamic model of the IDHS was developed based on energy balance principles. The dynamic model consists of sub-system models such as boiler, pipe network, heat exchanger, terminal heater and zone models. Simulation results of the dynamic responses show that the overall efficiency of the IDHS system is 78.7%, and the two highest heat loss components are the boiler heat losses and the secondary water makeup loss.

Discrete thermal element modelling of heat conduction in particle systems: Pipe-network model and transient analysis

In our recent work [Y.T. Feng, K. Han, C.F. Li, D.R.J. Owen. Discrete thermal element modelling of heat conduction in particle systems: basic formulations. Journal of Computational Physics. 227: 5072–5089, 2008], a novel numerical methodology, termed the discrete thermal element method (DTEM), is proposed for the modelling of heat conduction in systems involving a large number of circular particles in 2D cases. The method cannot be easily extended to transient analysis, which causes difficulties in combining the DTEM with the conventional discrete element method for modelling thermal/mechanical coupling problems in particle systems. This paper presents a simplified version of the DTEM, termed the pipe-network model, in which each particle is replaced by a simple thermal pipe-network connecting the particle centre with each contact zone associated with the particle. The model essentially neglects the direct heat transfer between the contact zones and thus significantly simplifies the solution procedure of the original DTEM. With this feature, transient heat conduction analysis can now be performed in a straightforward manner. In addition, the entire algorithmic structure of the pipe-network model is compatible with the discrete element method, leading to an effective scheme for simulating thermal–mechanical coupling problems. Numerical experiments are conducted to establish the solution accuracy of the proposed model.

Improved Control of Pressure Reducing Valves in Water Distribution Networks

The behavior of transients in water pipe networks is well understood but the influence of modulating control valves on this behavior is less well known. Experimental work on networks supplied through pressure reducing valves (PRVs) has demonstrated that, in certain conditions, undesirable phenomena such as sustained or slowly decaying oscillation and large pressure overshoot can occur. This paper presents results from modeling studies to investigate interaction between PRVs and water network transients. Transient pipe network models incorporating random demand are combined with a behavioral PRV model to demonstrate how the response of the system to changes in demand can produce large or persistent pressure variations, similar to those seen in practical experiments. A proportional-integral-derivative (PID) control mechanism, to replace the existing PRV hydraulic controller, is proposed and this alternative controller is shown to significantly improve the network response. PID controllers are commonly used in industrial settings and the methods described are easy to implement in practice.

Two modelling approaches to water-quality simulation in a flooded iron-ore mine (Saizerais, Lorraine, France): A semi-distributed chemical reactor model and a physically based distributed reactive transport pipe network model

The flooding of abandoned mines in the Lorraine Iron Basin (LIB) over the past 25 years has degraded the quality of the groundwater tapped for drinking water. High concentrations of dissolved sulphate have made the water unsuitable for human consumption. This problematic issue has led to the development of numerical tools to support water-resource management in mining contexts. Here we examine two modelling approaches using different numerical tools that we tested on the Saizerais flooded iron-ore mine (Lorraine, France). A first approach considers the Saizerais Mine as a network of two chemical reactors (NCR). The second approach is based on a physically distributed pipe network model (PNM) built with EPANET 2 software. This approach considers the mine as a network of pipes defined by their geometric and chemical parameters. Each reactor in the NCR model includes a detailed chemical model built to simulate quality evolution in the flooded mine water. However, in order to obtain a robust PNM, we simplified the detailed chemical model into a specific sulphate dissolution–precipitation model that is included as sulphate source/sink in both a NCR model and a pipe network model. Both the NCR model and the PNM, based on different numerical techniques, give good post-calibration agreement between the simulated and measured sulphate concentrations in the drinking-water well and overflow drift. The NCR model incorporating the detailed chemical model is useful when a detailed chemical behaviour at the overflow is needed. The PNM incorporating the simplified sulphate dissolution–precipitation model provides better information of the physics controlling the effect of flow and low flow zones, and the time of solid sulphate removal whereas the NCR model will underestimate clean-up time due to the complete mixing assumption. In conclusion, the detailed NCR model will give a first assessment of chemical processes at overflow, and in a second time, the PNM model will provide more detailed information on flow and chemical behaviour (dissolved sulphate concentrations, remaining mass of solid sulphate) in the network. Nevertheless, both modelling methods require hydrological and chemical parameters (recharge flow rate, outflows, volume of mine voids, mass of solids, kinetic constants of the dissolution–precipitation reactions), which are commonly not available for a mine and therefore call for calibration data.

Dynamic least-cost optimisation of wastewater system remedial works requirements

In recent years, there has been increasing concern for wastewater system failure and identification of optimal set of remedial works requirements. So far, several methodologies have been developed and applied in asset management activities by various water companies worldwide, but often with limited success. In order to fill the gap, there are several research projects that have been undertaken in exploring various algorithms to optimise remedial works requirements, but mostly for drinking water supply systems, and very limited work has been carried out for the wastewater assets. Some of the major deficiencies of commonly used methods can be found in either one or more of the following aspects: inadequate representation of systems complexity, incorporation of a dynamic model into the decision-making loop, the choice of an appropriate optimisation technique and experience in applying that technique. This paper is oriented towards resolving these issues and discusses a new approach for the optimisation of wastewater systems remedial works requirements. It is proposed that the optimal problem search is performed by a global optimisation tool (with various random search algorithms) and the system performance is simulated by the hydrodynamic pipe network model. The work on assembling all required elements and the development of an appropriate interface protocols between the two tools, aimed to decode the potential remedial solutions into the pipe network model and to calculate the corresponding scenario costs, is currently underway.

Karst Spring Responses Examined by Process‐Based Modeling

Ground water in karst terrains is highly vulnerable to contamination due to the rapid transport of contaminants through the highly conductive conduit system. For contamination risk assessment purposes, information about hydraulic and geometric characteristics of the conduits and their hydraulic interaction with the fissured porous rock is an important prerequisite. The relationship between aquifer characteristics and short-term responses to recharge events of both spring discharge and physicochemical parameters of the discharged water was examined using a process-based flow and transport model. In the respective software, a pipe-network model, representing fast conduit flow, is coupled to MODFLOW, which simulates flow in the fissured porous rock. This hybrid flow model was extended to include modules simulating heat and reactive solute transport in conduits. The application of this modeling tool demonstrates that variations of physicochemical parameters, such as solute concentration and water temperature, depend to a large extent on the intensity and duration of recharge events and provide information about the structure and geometry of the conduit system as well as about the interaction between conduits and fissured porous rock. Moreover, the responses of solute concentration and temperature of spring discharge appear to reflect different processes, thus complementing each other in the aquifer characterization.

Simulation of Hydropneumatic Tanks in Computer Pipe Network Models

Pipe network computer models of water systems that include hydropneumatic tanks can be used to evaluate performance of existing water systems or in the design of new distribution facilities. Pipe network models allow the modeling of storage tanks in which the free water surface is variable with the inflow and outflow. Most existing pipe network models do not allow direct input of hydropneumatic tanks. Some writers describe modeling of hydropneumatic tanks as a fixed diameter tank of an equivalent area based on the maximum and minimum operating pressures of the tank. In real hydropneumatic tanks, the pressure change due to input or output of water is greater as more water is stored in the tank. A relationship to define the geometry of a free water surface tank that would exactly simulate a hydropneumatic tank was derived which can be input into a pipe network model using the variable area tank feature.

Hybrid Approach for Modeling Wet Weather Response in Wastewater Systems

This paper presents a hybrid modeling approach for modeling flows within wastewater pipe networks. The approach utilizes the MOUSE model as a deterministic pipe network model and a radial basis function neural network (RBFNN) model as a stochastic error-correction model. Both models utilize rainfall as input, whereas the RBFNN utilizes MOUSE model flow predictions and its errors (residuals, differences) related to that prediction. The MOUSE model output provides an approximation of the hydrodynamic process, whereas the outputs of the trained RBFNN compensate for the output errors (residuals) of the MOUSE model. It is demonstrated that this approach is capable of reducing the model prediction error compared to the deterministic model when applied alone. It is also demonstrated that this approach generates more accurate results than hybrid models with linear stochastic components when compared for direct and iterative forecasts. The results achieved are promising, and the approach developed provides an innovative tool for achieving more accurate outputs.

Development of a coupled surface-groundwater-pipe network model for the sustainable management of karstic groundwater

This paper considers the hydrogeological simulation of groundwater movement in karstic regions using a hydrological modelling system (SHETRAN) which has been adapted for modelling flow in karstic aquifers. Flow and transport through karstic aquifers remains poorly understood, yet quantitative hydrogeological models are essential for developing and implementing groundwater protection policies. The new model has been developed and used within the STALAGMITE (Sustainable Management of Groundwater in Karstic Environments) project, funded by the European Commission. The SHETRAN model is physically based insofar as most of the parameters have some physical meaning. The SHETRAN model represents all of the key processes in the hydrological cycle, including subsurface flow in the saturated and unsaturated zones, surface flow over the ground surface and in channels, rainfall interception by vegetation canopies, evapotranspiration, snow-pack development and snowmelt. The modifications made to SHETRAN to simulate karstic aquifers are (1) the coupling of a pipe network model to a variably saturated, three-dimensional groundwater component (the VSS-NET component), to simulate flow under pressure in saturated conduits; (2) the coupling of surface water features (e.g. sinking streams or "ponors", and spring discharges) to the conduit system; (3) the addition of a preferential "bypass" flow mechanism to represent vertical infiltration through a high-conductivity epikarst zone. Lastly, a forward particle tracking routine has been developed to trace the path of hypothetical particles with matrix and pipe flow to springs or other discharge points. This component allows the definition of groundwater protection zones around a source for areas of the catchment (watershed) which are vulnerable to pollution from non-point sources (agriculture and forestry).

Basic research on key techniques related to urban 3D pipe network modeling

A new geometric modeling approach is introduced in this paper. First the principle of modeling of 3D pipe network is discussed in detail. Then the procedures of implementing pipe network visualization and system functions are presented. Last, several efficient methods for speeding up display of graphics are introduced. The new geometric modeling approach offers to people a new way to solve 3D visualization of complex urban pipe network.

Pipe network model for scaling of dynamic interfaces in porous media

We present a numerical study on the dynamics of imbibition fronts in porous media using a pipe network model. This model quantitatively reproduces the anomalous scaling behavior found in imbibition experiments [Phys. Rev. E 52, 5166 (1995)]. Using simple scaling arguments, we derive a new identity among the scaling exponents in agreement with the experimental results.

Valve Closure in Graph-Theoretical Models for Slow Transient Network Analysis

A valve closure algorithm is presented for inclusion within a slow transient (rigid water column) pipe network model. The algorithm is specifically formulated for (but not limited to) node-based, graph-theoretical models and is both direct and accurate. It is distinguished from conventional approaches by its direct assignment of the final discharge at closure to zero and subsequent use of the head loss at the closing valve to compute the flow rate in pipes incident to the closing valve. As a result, redistribution of residual flow prior to closure to these incident pipes is not required, leading to a less computationally demanding and more robust algorithm than previously published valve closure procedures. Application of the valve closure algorithm is illustrated in a pipe network, which also nicely demonstrates again the relation between rigid water column and water hammer models.

Discussion of “Modified Pipe Network Model for Incorporating Peak Demand Requirements” by Srinivasa Lingireddy, Don J. Wood, and Alan Nelson

Discussion of “Modified Pipe Network Model for Incorporating Peak Demand Requirements” by Srinivasa Lingireddy, Don J. Wood, and Alan Nelson

Discussion of “Modified Pipe Network Model for Incorporating Peak Demand Requirements” by Srinivasa Lingireddy, Don J. Wood, and Alan Nelson

Discussion of “Modified Pipe Network Model for Incorporating Peak Demand Requirements” by Srinivasa Lingireddy, Don J. Wood, and Alan Nelson

Frictional, diathermal flow of steam in a pipeline

Nonadiabatic one-dimensional flow of steam in elementary modules of pipe networks, i.e. straight pipes and fittings, has been considered. A simple method of determining the amount of condensed water, distributions of pressure and temperature along these modules has been developed. The problem of critical flow regime has been discussed and a general formula of checking for the presence of sonic velocities at arbitrary cross section of the pipeline has been given. When embedded into a supervising procedure, the described routines can be used to build a mathematical model of a steam pipe network of arbitrary topology. Numerical examples are included. A set of equations describing all the steam properties used in the calculations is given in the Appendix.