Analysis of Unsteady Friction Models Used in Engineering Software for Water Hammer Analysis: Implementation Case in WANDA

Transient events are frequent in water distribution systems. However, until now, most of the applications based on transient analyses are merely theoretical. Additionally, their implementation to real engineering problems is limited due to several physical phenomena accompanying transient waves, which are not accounted for in the classic approach, such as unsteady friction. This study investigates different unsteady friction models’ performance in terms of accuracy, efficiency, and reliability to determine the most-suited engineering practice. As a result of this comparison, Vitkovský’s unsteady friction model was found to be the best fit and was then implemented in WANDA commercial software. The implementation was verified with experimental data based on a reservoir–pipe–valve system. The model proved excellent performance; however, it was noticed that it fell short in simulating plastic pipes, where viscoelastic effects dominate. The upgraded software was then tested on different hydraulic networks with varying pipe materials and configurations. The model provided significant improvement to water hammer simulations with respect to wave shape, damping, and timing.