Investigation of transition from free surface to pressurized flow in a circular pipe

Trajkovic, B.; Ivetić, Marko; Calomino, Francesco; D’Ippolito, Antonino

doi:10.2166/wst.1999.0453

Cited by 40 publications

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“…Initial conditions q(x, 0) are assumed to be known, and boundary conditions q(0, t) and q(L, t) are assigned based on the network connectivity and external inputs described in Section 3.2. The Preissman slot approach has been used, for example, by Trajkovic et al [32], who compared the model with experimental data; by Kerger et al [16], who implemented an exact Riemann solver and introduced a "negative slot" modification to handle subatmospheric pressure; by León et al, [22], who allowed the pressure wave speed to vary slightly; and by Borsche and Klar [1], who used a hexagonal cross-section to simplify the area-height relationship. Other transient flow models for air and water in single pipes include a "two-component pressure" approach [37,34]; a single-equation model with a modified pressure term [3,4]; a two-component model [23]; and a three-phase model accounting for air, air-water mixture, and water [15].…”

Section: Model the Preissman Slot Formulationmentioning

confidence: 99%

“…The discharge coefficient C d = 0.78 and the contraction coefficient C c = 0.83, are empirical constants from experiment [32]. In this case, A ext = A in .…”

Section: Model the Preissman Slot Formulationmentioning

confidence: 99%

“…Experiments were performed in a single pipe of flow transitioning from open-channel to pressurized and back [32]. The experimenters used the Preismann slot to model their results, and their experiments have been revisited in several other studies [22,36].…”

Section: Experiments Of Trajkovic Et Al (1999)mentioning

confidence: 99%

“…The experimenters used the Preismann slot to model their results, and their experiments have been revisited in several other studies [22,36]. The experiments were performed in a single pipe of length L = 10 m and diameter D = 0.1 m, set at a slope of 2.7% as reported in [32]. The Manning roughness coefficient was estimated as 0.002 after examining modeling results for a small range of roughness coefficient values.…”

Section: Experiments Of Trajkovic Et Al (1999)mentioning

confidence: 99%

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Optimizing Intermittent Water Supply in Urban Pipe Distribution Networks

Lieb¹,

Rycroft²,

Wilkening³

2016

SIAM J. Appl. Math.

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Abstract. In many urban areas of the developing world, piped water is supplied only intermittently, as valves direct water to different parts of the water distribution system at different times. The flow is transient, and may transition between free-surface and pressurized, resulting in complex dynamical features with important consequences for water suppliers and users. Here, we develop a computational model of transition, transient pipe flow in a network, accounting for a wide variety of realistic boundary conditions. We validate the model against several published data sets, and demonstrate its use on a real pipe network. The model is extended to consider several optimization problems motivated by realistic scenarios. We demonstrate how to infer water flow in a small pipe network from a single pressure sensor, and show how to control water inflow to minimize damaging pressure transients.1. Introduction. From the dry taps of Mumbai to the dusty reservoirs of São Paolo, urban water scarcity is a common condition of the present, and a likely feature of the future. Hundreds of millions of people worldwide are connected to water distribution systems subject to intermittency. This intermittent water supply may take many forms, from unexpected disruptions to planned supply cycles where pipes are filled and emptied regularly to shift water between different parts of the network at different times [17,33]. In Mumbai, for example, Vaivaramoorthy [33] reports that on average, residents have water flowing from their taps less than 8 out of 24 hours. Intermittent supply is often inequitable, with low-income neighborhoods experiencing lower water pressure and shorter supply durations than high-income ones [31]. Intermittent supply not only limits water availability, but also compromises water quality and damages infrastructure. With field data from urban India, Kumpel and Nelson [18] quantified the deleterious effect of intermittency on water quality, showing that both the initial flushing of water through empty pipes-as well as periods of low pressure-corresponded with periods of increased turbidity and bacterial contamination. Christodoulou [7] observed when that a drought in Cypress ushered in two years of intermittent supply, pipe ruptures increased by 30%-70% per year.Whereas intermittent water supply creates challenges for water managers and water users, the phenomenon creates opportunities for applied mathematics. It is an interesting and difficult mathematical problem to efficiently model transient pipe flow in networks-including transitions to and from pressurized states-with uncertain or complex boundary conditions. In this work we introduce a framework to not only describe intermittent water supply, but also use optimization to improve either our description of the system, or the operation of the described system in order to reduce risks such as infrastructure damage.Intermittent supply falls in somewhat of a modeling gap. Water distribution software abounds, including the free and open source software EPANET ...

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Section: Model the Preissman Slot Formulationmentioning

confidence: 99%

“…The discharge coefficient C d = 0.78 and the contraction coefficient C c = 0.83, are empirical constants from experiment [32]. In this case, A ext = A in .…”

Section: Model the Preissman Slot Formulationmentioning

confidence: 99%

Section: Experiments Of Trajkovic Et Al (1999)mentioning

confidence: 99%

Section: Experiments Of Trajkovic Et Al (1999)mentioning

confidence: 99%

See 2 more Smart Citations

Optimizing Intermittent Water Supply in Urban Pipe Distribution Networks

Lieb¹,

Rycroft²,

Wilkening³

2016

SIAM J. Appl. Math.

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“…To study the transition from free surface to pressurized flow in sewers during storm events, Trajkovic et al (1999) conducted experiments in a test rig consisting of a circular pipe with downward slope and gates at the upstream and downstream ends. The overall pipe length was about 10 m and the pipe diameter was 100 mm.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Rapid Filling of a Large-Scale Pipeline

et al. 2014

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. ABSTRACTThis study presents results from detailed experiments of the two-phase pressurized flow behavior during the rapid filling of a large-scale pipeline. The physical scale of this experiment is close to the practical situation in many industrial plants. Pressure transducers, water level meters, thermometers, void fraction meters and flow meters were used to measure the two-phase unsteady flow dynamics. The main focus is on the water-air interface evolution during filling and the overall behavior of the lengthening water column. It is observed that the leading liquid front does not entirely fill the pipe cross section; flow stratification and mixing occurs. Although flow regime transition is a rather complex phenomenon, certain features of the observed transition pattern are explained qualitatively and quantitatively. The water flow during the entire filling behaves as a rigid column as the open empty pipe in front of the water column provides sufficient room for the water column to occupy without invoking air compressibility effects. As a preliminary evaluation of how these large-scale experiments can feed into improving mathematical modeling of rapid pipe filling, a comparison with a typical one-dimensional rigid-column model is made.

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A fast universal solver for 1D continuous and discontinuous steady flows in rivers and pipes

Kerger

Archambeau

Erpicum

et al. 2011

Numerical Methods in Fluids

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IntroductionOne dimensional numerical simulation of free-surface and pressurized flows is a useful engineering tool for a wide range of practical applications in civil engineering. The method can be used as long as no 2D and 3D hydraulic effects are predominant and must be thus taken into account. For instance, large rivers networks are often managed and developed by means of 1D models [1,2]. Similarly, simulation of pressurized flow in pipes networks such as water supply or sewer systems relies traditionally on such models [3,4]. Finally, 1D models can be reliably considered in the design process of many hydraulic structures such as water intake, bottom outlet tailrace tunnel, flushing galleries in dams [5]. On account of the large number of practical applications concerned, an efficient prediction of 1D flow features is an obvious need. Developing a unified 1D model for all the situations of interest in civil engineering remains however challenging. Various flow patterns may indeed coexist in actual situations:1. Free surface flows, where supercritical, subcritical and transcritical conditions could co-exist [2], are usually modelled, including the discontinuities (hydraulic jump), on the basis of the conservative Saint-Venant equations [6,7]. 2. Pressurized flows are traditionally described by the water hammer equations [4]. 3. Mixed flows, characterized by a simultaneous occurrence of free-surface and pressurized flow, are still nowadays an issue of research [8][9][10][11] for its mathematical description and its numerical solution. To achieve our purpose to develop a universal solver handling free-surface, pressurized and mixed flow, it is then required 1. to establish a unified mathematical model which overcomes the dissimilarity between the sets of equations describing pressurized and free-surface flows; 2. to set an efficient resolution scheme for this model. As previously mentioned, different mathematical approaches to describe free-surface, pressurized and mixed flow in a unified framework have been developed to date and are still subject to many research. Shock-tracking methods consists in solving separately free-surface and pressurized flows through different sets of equations [12,13]. Rigid Water Column Approach treats each phase separately on the basis of a specific set of equations in focusing on the air behaviour [14]. Nevertheless, such algorithms are very complicated and casespecific. Finally, the so-called shock-capturing approach is a family of method which computes pressurized and free-surface flows by using a single set of equations [8][9][10][11] . In this paper, such an approach is used, based on the model of the Preissmann slot [15]. In particular, this paper focuses on steady state flows which are of great interest for engineers. Design guidelines for many hydraulic structures specify indeed that specific critical steady states have to be addressed. Practitioners should then rely on robust and efficient 1D solvers suitable for each flow pattern (free-surface, pressurized and mixed) in o...

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Investigation of transition from free surface to pressurized flow in a circular pipe

Cited by 40 publications

References 0 publications

Optimizing Intermittent Water Supply in Urban Pipe Distribution Networks

Optimizing Intermittent Water Supply in Urban Pipe Distribution Networks

Experimental Investigation on Rapid Filling of a Large-Scale Pipeline

A fast universal solver for 1D continuous and discontinuous steady flows in rivers and pipes

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