Enhancing Water Quality Predictions in Water Distribution Networks: Development and Integration of an RSM-Based Incomplete Mixing Model

Improving the accuracy of Water Distribution Network (WDN) water quality models presents a significant challenge, particularly due to the incomplete mixing phenomena at internal junctions. In this study, CFD numerical simulations were conducted to identify key factors affecting solute mixing at cross, double-T, and H junctions. It was found that the inlet and outlet Reynolds number ratios significantly impact mixing efficiency at all three types of junctions, with the spacing at double-T junctions being particularly critical. An incomplete mixing model was developed based on the Response Surface Methodology (RSM). By integrating the RSM-based Incomplete Mixing Model (RSM-IMM) into EPANET or similar hydraulic and water quality modeling software, engineers and researchers can improve predictions of water quality parameters, thereby making more informed decisions in the management and operation of WDNs.