EPANET INP Code for Incomplete Mixing Model in Cross Junctions for Water Distribution Networks

EPANET can be used to simulate quality on water distribution networks. The EPANET model considers that the mixing on cross junctions of pipes is complete, including the cases of two contiguous inlets and two contiguous outlets. The output concentration of this model is the same value on the two outlets. This research proposes a code to generate an INP file for EPANET but with an incomplete mixing scenario in the crossings. The cross junctions are identified, and their hydraulic and concentration conditions are analyzed for each quality time step. Bypass pipes are included in the model to remove concentrations generated by the complete mixing model, preserve continuity in water quality and ensure the correct allocation of concentration. The concentration at the outlets is obtained by a system of polynomial equations representing the incomplete mixing model as a function of the hydraulic and concentration at the junction inlets. The outlets' concentrations are incorporated by setpoint boosters. Validations are described to demonstrate the achievement of the new code. An average relative concentration difference of up to 14% is obtained in networks with different scenarios for the two mixing models.