scholarly journals Reformulated Co-Tree Flows Method Competitive with the Global Gradient Algorithm for Solving Water Distribution System Equations

2014 ◽  
Vol 140 (12) ◽  
pp. 04014040 ◽  
Author(s):  
Sylvan Elhay ◽  
Angus R. Simpson ◽  
Jochen Deuerlein ◽  
Bradley Alexander ◽  
Wil H. A. Schilders
Keyword(s):  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Gradient Algorithm ◽  
Global Gradient Algorithm ◽  
System Equations

scholarly journals Equivalent hydraulic resistance to simulate pipes subject to diffuse outflows

2011 ◽  
Vol 14 (1) ◽  
pp. 65-74 ◽  
Author(s):  
M. Ferrante ◽  
E. Todini ◽  
C. Massari ◽  
B. Brunone ◽  
S. Meniconi
Keyword(s):  
Hydraulic Resistance ◽  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Distribution Network ◽  
Network Models ◽  
Water Distribution Network ◽  
Simulation Models ◽  
Gradient Algorithm ◽  
Present Generation

In water distribution network simulation models, pipes subject to diffuse outflow, either due to connections or to distributed demand or to leaks along their length, are generally converted into pipe elements only subject to lumped demand at their ending nodes. This approximation, which disregards the flow variation along the pipes, generates a loss of axial momentum, which is not correctly taken into account in the present generation of water distribution network models. In this paper a correction to the lumped demand approximation is provided and this equivalence is analyzed within the framework of the Global Gradient Algorithm. This is obtained through a correction of the pipe hydraulic resistance; this approach has proven to be more effective than the use of an asymmetrical lumped demand of the total distributed outflow at the pipe ending nodes. In order to assess the effect of the introduced correction, an application to a simple water distribution system is finally provided.

scholarly journals Extending the global gradient algorithm to unsteady flow extended period simulations of water distribution systems

2010 ◽  
Vol 13 (2) ◽  
pp. 167-180 ◽  
Author(s):  
Ezio Todini
Keyword(s):  
Unsteady Flow ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Extended Period ◽  
Distribution Networks ◽  
Gradient Algorithm ◽  
Integration Time ◽  
Original Algorithm ◽  
Global Gradient Algorithm

This paper introduces an extension of the Global Gradient Algorithm (GGA) to directly solve unsteady flow problems arising from the presence of variable head water storage devices, such as tanks, in Extended Period Simulations (EPS) of looped water distribution networks (WDN). Such a modification of the original algorithm was motivated by the need to overcome oscillations and instabilities reported by several users of EPANET, a worldwide available package, which uses the GGA to solve the looped WDN equations. The set of partial differential equations describing the time and space behaviour of a water distribution system is here presented. It is shown how an unsteady flow GGA can be derived by simple modifications of the original steady-state GGA. The performances of the new algorithm, referred to as EPS-GGA, are compared with the results provided by EPANET on an extremely simplified example, the solution of which is qualitatively known. As opposed to EPANET which shows significant instabilities, the EPS-GGA is stable under a wide variety of increasing integration time intervals.

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