Computational Hydraulics of an Underground Wastewater Drainage System

A high-fidelity computational method for modeling multi-phase wastewater flow is developed to understand the unsteady flow structures so as to facilitate the design of components of a typical underground wastewater drainage system consisting of a tangential vortex drop shaft, de-aeration chamber, and an adit. Two-phase flow consisting of air and water is addressed in this study. It is found that the flow structure is profoundly affected by hydraulic structures such as the de-aeration chamber and the air-vent system. The commonly accepted practice is to consider only the approach flow, vortex intake, and the drop shaft for analysis. The present study shows that the full hydraulic system should be modeled in an integrated manner to ensure a safe design.