Mixing at Cross Junctions in Water Distribution Systems. II: Experimental Study

The present experimental study focuses on the characterization of complex mixing phenomena at pipe intersections within pressurized water distribution networks. To examine the complete mixing assumption at a cross junction, a series of experiments were conducted in the turbulent regime $(\mathsf{R}>\mathrm{10,000})$ . The experimental setup consists of a cross junction with various sensors, pumps, and a data acquisition system to accurately measure solute concentration. Selected experimental results are compared to computational fluid dynamics (CFD) results. In addition, the water quality model associated with a standard water distribution network simulator (EPANET) was reevaluated based on CFD and experimental data. Corrections based on experimental results are incorporated into EPANET (AZRED 1.0) for use in a case study. The study concludes that the complete mixing assumption can potentially create considerable errors in water quality modeling. Further, severe errors are likely to occur in systems with many cross type junctions due to bifurcation of the incoming flows.