Stochastic Approach for the Analysis of Demand Induced Transients in Real Water Distribution Systems

Marsili, Valentina; Meniconi, Silvia; Alvisi, Stefano; Brunone, Bruno; Franchini, Marco

doi:10.1061/(asce)wr.1943-5452.0001498

Cited by 15 publications

(12 citation statements)

References 51 publications

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“…Studies demonstrate that the omission of such a term in the numerical model produces a smaller decay of the pressure with respect to the measured ones (e.g., Ebacher et al, 2011). As shown by Marsili et al (2022), the choice of the unsteady friction model cannot disregard the characteristics of the investigated pipe system. In the case of a complex WDN with a significant number of users, the need is to make the numerical simulations affordable in terms of computational time, data storage, and memory.…”

Section: Transient Modelingmentioning

confidence: 99%

Extending the Application of Connectivity Metrics for Characterizing the Dynamic Behavior of Water Distribution Networks

Marsili

Alvisi

Maietta

et al. 2023

Water Resources Research

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Water distribution networks (WDNs) are complex combinations of nodes and links, and the current tendency is to modify their topological structure through the closure of isolation valves for monitoring and water quality reasons. For their analysis, several approaches based on graph theory have recently been proposed, mainly considering steady‐state flow conditions. However, in their real functioning, WDNs are continuously subjected to pressure transients generated by maneuvers on regulation devices or by users' activity. This study investigates the application of some metrics from graph theory, already used in the context of steady‐state analysis, for assessing the effects of changes in the topological structure of a network—due for example, to sectorization or branching operations—on its transient response when subjected to maneuvers on devices such as hydrants, pumps, etc. or users' activity. The analysis shows that some connectivity metrics can effectively reflect the dynamic pressure behavior of the network and, thus, provide useful indications for design and management operations taking into account unsteady flow features.

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Section: Transient Modelingmentioning

confidence: 99%

Extending the Application of Connectivity Metrics for Characterizing the Dynamic Behavior of Water Distribution Networks

Marsili

Alvisi

Maietta

et al. 2023

Water Resources Research

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“…Finally, in order to consider realistic and randomly varying water consumption patterns at different nodes of the system, a test featuring 1 hr of random water consumption variations in all the three end-users (i.e., nodes 5u, 6u, and 7u), for more than one hundred and fifty opening and closing maneuvers, is performed (test series #5). The water consumption pattern simulated in each node is definitively representative of the operations of users in pipe networks since it has been obtained by field monitoring of real users (Marsili et al, 2021(Marsili et al, , 2022.…”

Section: Laboratory Transient Testsmentioning

confidence: 99%

“…The second respect concerns the characteristics of these two components, with the diameter of the main pipes being significantly larger than the one of the service lines. In Marsili et al (2021Marsili et al ( , 2022, the pressure signals acquired in a real WDN in ordinary operational conditions (i.e., with no maneuvers on pumps or valves in the main pipes) indicate that the short term pressure variations occurring in the main pipes are due to the water consumption changes. In Lee et al (2012), laboratory experiments concern a limited (i.e., six) number of tests on a tree layout system.…”

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confidence: 99%

Consumption Change‐Induced Transients in a Water Distribution Network: Laboratory Tests in a Looped System

Meniconi

Maietta

Alvisi

et al. 2022

Water Resources Research

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In pipe networks, the pressure plays a key role and, in particular, pressure variations due to transients can induce additional stresses not only on pipes, but also on the other components, such as junctions and devices.Traditionally, in transmission mains attention is focused on the effects of a valve maneuver, carried out to set an appropriate discharge, or pump trip that can give rise to severe overpressures (Liou & Wylie, 2016;Meniconi et al., 2018;. Very different is the approach with respect to transients in water distribution networks (WDNs) which are the topic of this paper. Precisely, the effects of the transients in WDNs are often underestimated in the belief that such systems are always intrinsically self-protected against them. Such a conviction is based on the assumption that a large part of the generated pressure waves would exit through the consumers that, when active, behave as pressure relief valves. Thus, pipe breaks in WDNs are attributed to the large mean pressure or, in case the pressure regime is considered as appropriate, the inaccurate installation of pipes, additional loads due to traffic, and the large number of connections that undermine the integrity of the system. As a remedy against the large pressure regime and leakage, in WDNs the installation of pressure reducing valves (PRVs) is a common practice (e.g., Meniconi et al., 2017).Posed the question in these terms, in many cases it is arduous identifying the actual cause of the large leakage that characterizes only some parts of a WDN that exhibit no clear differences with respect to other ones in terms of pipe material, maintenance, external loads, as well as the pressure values, usually monitored at a low frequency. A possible explanation of such a feature could derive from a proper identification of the nature of the actually dangerous transients and the different exposure to them of individual parts of the considered WDN. With the aim of explaining the results achieved by this paper and pointing out the open questions and urgent matter to address, a literature review is offered below.Numerous papers analyze numerically the transient behavior of a WDN. More in details, the numerical papers deal with four main aspects: (a) the use of transients for detecting an anomaly (

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“…Waveform comparison suggests that the CB model better fits for the CFD model as it considers the velocity time history in calculating the unsteady friction term. It should be noted that despite a higher numerical resolution in detailed flow field analysis, CFD models may still have limitations in terms of the neglected fluid-structure energy exchange, simplified laminar assumption of wall shear law, and obviously high computational cost, when compared with eligible IAB or CB models in practical application for large-scale hydraulic systems (Mandair et al 2020;Marsili et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Unsteady friction model modified with compression–expansion effects in transient pipe flow

Cao

Wang

Deng

et al. 2022

Journal of Water Supply: Research and Technology-Aqua

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This paper aims to modify the conventional one-coefficient instantaneous acceleration-based (IAB) model for better prediction of unsteady friction behavior. In this work, the energy dissipation caused by viscous stress during fluid volume compression–expansion (CE) was derived from the compressible Navier–Stokes equation. It is found that the energy dissipation term can be expressed by the product of the second-order partial derivative of velocity in space and the second viscosity coefficient. On this basis, a modified IAB-CE model was developed with the energy dissipation term and solved by the method of characteristic (MOC). The numerical results obtained from the modified model showed a good agreement with the four test cases, where the relative errors are improved by 0.26, 2.03, 9.56, and 36.67%, compared with the results from the original IAB model. The estimation for wave peak and valley is improved as well. Furthermore, the Bradley equation can be applied to establish the relationship between the dissipation coefficient and the Reynolds number. The modified model developed in this study takes into account the fluid CE effects and improves the prediction accuracy of wave amplitude of unsteady flow.

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Stochastic Approach for the Analysis of Demand Induced Transients in Real Water Distribution Systems

Cited by 15 publications

References 51 publications

Extending the Application of Connectivity Metrics for Characterizing the Dynamic Behavior of Water Distribution Networks

Extending the Application of Connectivity Metrics for Characterizing the Dynamic Behavior of Water Distribution Networks

Consumption Change‐Induced Transients in a Water Distribution Network: Laboratory Tests in a Looped System

Unsteady friction model modified with compression–expansion effects in transient pipe flow

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