Contaminant intrusion in water distribution systems (WDSs) poses a significant challenge, necessitating precise numerical models to estimate intruded contaminants and predict their fate. This study introduces a novel full Lagrangian solver for evaluating contaminant intrusion and extrusion patterns, demonstrating superior accuracy and efficiency compared with traditional Eulerian methods. The Lagrangian approach reduces calculation time by more than 80% while maintaining strong correlation with experimental data (R2=0.9741). A comprehensive sensitivity analysis of 36 distinct scenarios reveals relative pressure head along the pipe as the primary factor influencing contaminant intrusion volumes. Notably, higher re-extrusion rates occur near downstream valves, reaching up to 68%, whereas midpipe sections exhibit the highest rates of contaminant intrusion and trapping. These findings enhance understanding of contaminant transport dynamics and improve computational efficiency in simulating WDS contamination events, ultimately supporting better management strategies for water supply systems.
Payesteh et al. (2026) studied this question.