Improving the Efficiency of the Loop Method for the Simulation of Water Distribution Systems

Abstract

analysis problems, where the hydraulic simulation has to be repeated many times. Among 7 the methods used for hydraulic solvers, the most prominent nowadays is the global gradi-8 ent algorithm (GGA), based on a hybrid node-loop formulation and used by the software 9 package Epanet. Earlier, another method based just on loop flow equations was proposed, 10 which presents the advantage that it leads to a system matrix which is in most cases much 11 smaller than in the GGA method, but has also some disadvantages, mainly a less sparse 12 system matrix, and the fact that introducing some types of valves requires the redefinition 13 of the set of network loops initially defined. 14The contribution of this paper is to present solutions for overcoming the mentioned 15 disadvantages of the method based on loop flow equations. In particular, efficient procedures 16 are shown for selecting the network loops so as to achieve a highly sparse matrix, and methods 17 are presented to incorporate check valves and automatic control valves, while avoiding the 18 need to redefine the loops initially selected.

Improving the performance of water distribution systems’ simulation on multicore systems

“…We present complete results on a set of test networks, showing better results than existing related work. The results also extend those of [5], by considering networks with automatic valves.…”

“…An alternative to the GGA is the loop method [11], which is also a Newton-Raphson process working with a sparse, symmetric positive definite matrix. However, the size of the matrix is in this case n l ×n l , where n l = m−n is the number of independent loops that can be found in the network, which is usually much smaller that n. Some recent papers [5,7,10,2,1] have addressed the loop method as a competitive alternative to GGA. The authors developed contributions to this method, with the corresponding implementation [5].…”

“…This paper explores the use of OpenMP to accelerate the simulation of WDS, extending the work of the authors both in [4] and [5]. While [4] only considers the parallelization of Epanet, this paper also tackles that of the loop method.…”

“…Recently, several papers [7,8,10,2,1] have considered the loop method for simulation of WDS, first introduced in [11], as an alternative to the more widely used Global Gradient Algorithm (GGA), implemented in Epanet. The authors presented in [5] some contributions to the loop method, with an efficient implementation that is shown to be faster than Epanet for the test networks considered.…”

Limitations of demand- and pressure-driven modeling for large deficient networks

“…Elhay et al (2014) use a tree-cotree decomposition and take advantage of the fact that loop methods are null space methods. Alvarruiz et al (2015) have shown that loops can be defined without tree-cotree decomposition to increase the sparsity of the iteration matrix. Abraham and Stoianov (2015) conclude that loop methods are more efficient than GGA in most of the cases if minimal loops are defined and partial update of head losses and matrix products are used to further reduce computational complexity.…”