Hydraulic Analysis of Intermittent Water-Distribution Networks Considering Partial-Flow Regimes

Modeling intermittent water distribution networks (WDNs) requires effective incorporation of the transient flow conditions, including the transitions from pressurized to partial flow regimes and the inverse associated with periodic filling and emptying of pipes. Most existing hydraulic analysis models fail to account for the partial-flow conditions, and due to this reason, they cannot be directly applied for practical situations. This paper presents an improved pressure-dependent analysis (PDA) model, the PDA-PF model, integrating partial-flow characteristics in the algorithm. The PDA-PF model was developed based on the presumption that the pressure-deficiency triggers partial flows in pipes. The outflows at the demand nodes of highly intermittent WDNs are represented as uncontrolled orifice-based demands. In analyzing the pipe flows, the PDA-PF model performed better than the established models. The suitability of the proposed model for conducting extended period analysis was demonstrated by applying it to a real-world highly intermittent WDN of a municipality of India. Under the circumstances considered, partial-flow conditions existed in the distribution pipes for one-fourth of the total flow duration. The residual flows caused by the emptying of the pipes increased the volumetric water demand satisfaction at the low-elevation nodes of the considered WDN.