NETWORK LINEAR-PROGRAMMING AS PIPE NETWORK HYDRAULIC ANALYSIS TOOL

An accurate network linear programming (NLP) algorithm for the hydraul ic analysis of water pipe networks is developed and compared with dire ct equation solving techniques. Accuracy is achieved by the use of a n ovel iterative scheme in which successive linear approximations to the nonlinear head loss equations are refined for each pipe in the region of the emerging solution. The use of primal-dual and simplex method N LP solvers in the iterative strategy is investigated, with a hybrid sc heme being shown to reduce execution times by an order of magnitude. N evertheless, the direct equation solving algorithm of Todini and Pilat i remains much more efficient than the best NLP algorithm. A new algor ithm for the analysis of locally controlled feedback devices is develo ped for inclusion in the NLP strategy. The uniqueness of pipe network hydraulic solutions is also investigated. Although some doubt has been expressed regarding uniqueness of solutions to networks that contain locally controlled feedback devices, evidence of nonuniqueness has not been forthcoming. Arguments in support of unique solutions for such n etworks are presented.