Evaluation of solute mixing in water distribution pipe junctions

Abstract

Growing public concern about potential contaminant transport in water distribution systems has increased the use of models to assess risk and detect sources of contamination. The movement and distribution of contaminants depend largely on mixing at pipe junctions, where different flow rates and contaminant concentrations can exist. This article presents experimental observations of solute mixing in various pipe junction configurations. Analytical models are derived for each configuration, and results are compared with experimental data. A key finding—that impinging fluid streams within a junction often do not mix completely—is contrary to the most common assumption of complete mixing in pipe junctions. This study finds that if concentrations of two incoming fluid streams differ, they tend to bifurcate and reflect off one another, affecting subsequent solute distribution and mixing of fluid streams. The authors introduce a new bulk‐advective mixing (BAM) model that has been shown to accurately represent this behavior and lead to more accurate water quality assessments.