Ingenieria

water storage and distribution

The authors compared the formulation and computational performance of two numerical methods for modeling hydraulic transients in water distribution systems. One method is Eulerian-based, and the other is Lagrangian-based. The Eulerian approach explicitly solves the hyperbolic partial differential equations of continuity and momentum and updates the hydraulic state of the system in fixed grid points as time is advanced in uniform increments. The Lagrangian approach tracks the movement and transformation of pressure waves and updates the hydraulic state of the system at fixed or variable time intervals at times when a change actually occurs. Each method was encoded into an existing hydraulic simulation model that gave initial pressure and flow distribution and was tested on networks of varying size and complexity under equal accuracy tolerance. Results indicated that the accuracy ofthe methods was comparable, butthatthe Lagrangian method was more computationally efficient for analysis of large water distribution systems.

Numerical methods for modeling transient flow in distribution systems
BY DON J. WOOD. SRINIVASA LlNGIREDDY, PAUL F. BOULOS. BRYAN W KARNEY. AND DAVID L. MCF'HI::RSON

ompurcr models for simularing rhe hydraulic and water qualitv hehav101' of water di~trihution S\stellls havc heen availahlc for many years. Rccenth these lllodc!" ha\l: hccn extended to analyze hniraulic tran"iCllt, as \\'ell. In thc p~l';t, most transient analvscs were pcrformed onlv on large translllission mains u,ing highly skcletonized modcls for engincering design; propriet,HY transicnt computer prograllls \VelT largely Iilllired to "pecialist conslllting companies, research organizatiotls, and univcrsitics. In ,1ddition to improvcd design and opcration ()f \Varer distrihlltion sysrellls, a driving force behitld the tremi toward increased analysis of hvdralllic tratl,icnts has heen rhe gro\\'ing ,l\varctless th,n hydralllic transicnts can