Comparison between the two-component pressure approach and current transient flow solvers

Vasconcelos, José G.; Wright, Steven J.

doi:10.1080/00221686.2007.9521758

Cited by 42 publications

(31 citation statements)

References 15 publications

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“…In this textbook example, similar to a case presented by Vasconcelos et al [36], a sudden valve closure gives rise to a so-called water hammer phenomenon in a pressurized pipe, whereby a shock wave of high pressure travels Figure 4.2 show the time evolution of the nondimensionalized pressure head H(x = L, t)/H 0 at the valve and the discharge Q(x = 0, t)/Q 0 at the upstream end. The modeled results agree with the classical water hammer equations [40], which assert that for a pressure wave propagating in pressurized pipe, the relationship between the change in pressure head ∆H and the change in velocity ∆V = ∆Q/A f is…”

Section: Watermentioning

confidence: 97%

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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: Watermentioning

confidence: 97%

“…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].…”

Section: Experiments Of Trajkovic Et Al (1999)mentioning

confidence: 99%

Optimizing Intermittent Water Supply in Urban Pipe Distribution Networks

Lieb¹,

Rycroft²,

Wilkening³

2016

SIAM J. Appl. Math.

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“…Preissmann slot models regenerate free-surface flows in regions with low piezometric head, even if no ventilation is present. The DPA model has been proposed very recently, but initial tests showed its capacity to simulate diverse flow conditions and replicate the results from other transient flow models (Vasconcelos and Wright, 2005b).…”

Section: Discussionmentioning

confidence: 99%

“…A new alternative to mitigate the problem was proposed by Vasconcelos and Wright (2005b) by applying a numerical filter to the modeled results. This filter is designed to reduce the amplitude of the oscillations, and is based on a Fast-Fourier Transform procedure (FFT), as suggested by Press et al (1989).…”

Section: Numerical Oscillations In Flow Regime Transition Simulationsmentioning

confidence: 99%

Current Issues on Modeling Extreme Inflows in Stormwater Systems

Vasconcelos

Wright

Roe

2006

JWMM

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The increasing availability of different numerical models to simulate flow in storm sewers has raised several questions on the applicability of these models in the simulation of extreme inflow conditions. These issues include accurate modeling and prediction of bores, flow regime transition into pressurized flow and the possibility of air pocket entrapment and the subsequent effect on the system. With regards to bore description, the issue is not limited to the choice of equations for the problem solution, but includes the selection of numerical schemes that will ensure the correct bore propagation speed. It will be shown that the selection of the variables used to solve the mass and momentum equations has an impact in the solution of discontinuous flows. It will also be seen that numerical models without shock-capturing capabilities have limited ability to model flow discontinuities.Flow regime transition models can be divided into shock-fitting or shock-capturing approaches, each group of approaches with particular strengths and limitations. Due to the popularity of Preissmann slot-based models, including the soon-to-be released SWMM 5, a more detailed discussion on the issues of this approach is provided. Some new model improvements to shock-capturing approaches are presented, including a new conceptual model for simulating sewer surcharging referred to as the Decoupled Pressure Approach.

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“…The free surface and pressurized flows are computed by means of a single set of equations. Only four models appear to fall into this category: the Preissmann slot and its improvements (Leon et al 2008, Kerger et al 2009), the two-component pressure approach (TPA) (Vasconcelos and Wright 2007), the dual model , and the kinetic model . Further, only two references propose to integrate air-water interactions into a shock-capturing model.…”

Section: Introductionmentioning

confidence: 99%