High-Fidelity Simulation of the Influence of Local Geometry on Mixing in Crosses in Water Distribution Systems

Network simulation models for water distribution systems typically assume the mixing at pipe intersections is complete and instantaneous. Recent data show that mixing may be incomplete at pipe junctions (pipe crosses and tees) under most conditions. In general, computational fluid dynamic (CFD) simulations agree with the experimental data, establishing confidence in the CFD approach for application to other situations. However, in the case of unequal inlet flow rates and equal outlet flow rates in a cross, the simulation results and experimental data show significantly different results. The reasons for this discrepancy are investigated, and a revised model is developed that is consistent with the experimental data.