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The pipe component of a water distribution network (WDN) is sized based on the fixed design demand considering a peak factor and design period. Simulation of the designed network by a hydraulic solver provides nodal pressure head, head loss, velocity, and flow in each pipe as the prime outputs for the design demand, and it can also be used for extended-period simulation for a particular demand pattern over the supply hours. But, in reality, the behavior of the network does not match with such a result in an intermittent water supply (IWS) system due to the fact that all house service connections behave as an uncontrolled orifice. This has made it a challenging task in understanding and in predicting the behavior of the networks by the municipal engineer once the water starts flowing through the house service connections (HSCs). Though the municipal engineer provides the same pipe size for HSCs to all residences, the flow received by each house could vary based on the available pressure head at the ferrule point of the main water supply pipeline. In reality, maintaining constant pressure at each HSC is not feasible due to frictional head loss. Hence, variation in flow at the HSC is inevitable even with a small water supply system. This paper illustrates how to simulate the behavior of an IWS system based on the number of HSCs provided to each pipeline using a hydraulic solver. Hydraulic simulation of the water distribution network that provides IWS to consumers can be implemented easily by adding a fictitious node by assigning an appropriate emitter coefficient to each demand node through a fictitious link having a check valve in it. The method for finding the appropriate value of the emitter coefficient that helps in simulating HSCs is illustrated in the present work. [ABSTRACT FROM AUTHOR]

The range of pipe roughness values in both cases (triangular and trapezoidal) at the 0 HT ht level is the same, i.e., 110 to 130. For example, the minimum and maximum values obtained by the authors for HT ht are 8.88 and HT ht , while Sivakumar et al. ([5]) reported 5.81 and HT ht . Because the range of pipe roughness values at the 0 HT ht level in both triangular and trapezoidal cases is the same, MFs of pipe discharges and nodal heads at the 0 HT ht level should be identical. However, for other HT ht levels, these are different. [Extracted from the article]

A similar analysis is not applicable for Case Study 2 because the settings of the HT ht values are 0 for both PSVs and emitters. Hence, the discussers used PSV settings of zero instead of the HT ht values given in Table 2 of the original paper. The probable reason behind the authors' incorrect results for HT ht and 1.5 is that the default value of 0.5 might have been used for the global emitter exponent. [Extracted from the article]

This document provides a summary of a paper titled "Head-Drop Method for the Modeling of Pressure Reducing Valves and Variable Speed Pumps in Water Distribution Networks." The paper introduces the head-drop method for water distribution networks with pressure-regulating devices and presents an algorithm for pressure reducing valves (PRVs). The authors also extend the method to pressure-sustaining valves (PSVs) and implement it in the global gradient algorithm. The document discusses the results of a simulation comparing the head-drop method with a hybrid simulator, highlighting the importance of using criteria 1 and 2 together and setting the head drop for open valves to zero. [Extracted from the article]

Consider a PRV placed in pipe HT ht to control the pressure at its downstream node. [Extracted from the article]

The following corrections should be made to the original paper: Step 3 in the "Methodology" section should read: 3. Run the GGA until the sum of all link flow and emitter outflow changes divided by the sum of all link flows and emitter outflows is less than a specified stopping tolerance HT ht . [Extracted from the article]