Improvement for Practical Application of Time-Marching Approach for Steady Flows in Pipelines

Abstract

Time-marching approach (TMA) for finding steady flows in pipelines, using a water hammer analysis based on the characteristics method, is improved to be practical for the hydraulic design of large pipelines: a basic idea and algorithm for TMA-calculation is clarified when the Hazen-Williams' formula is incorporated into the head loss relation. The existing method for approximating a spectral radius defining the speed of convergence to a steady solution is revised to give more stable computational results, in addition to an algorithm for renewal of time-step sizes. The reformed TMA is examined and discussed through comparisons among numerical results computed with some kinds of time-marching approaches for a typical network system.