Evaluation of Mathematical Model Alternatives for the Simulation of Unsteady, Two-Phase Flows in Urban Water Systems

摘要

Rapid filling flows in stormwater systems during rain events has been cause of diverse operational problems and as result this has been investigated by a significant group of researchers to date. Frequently in these studies, a variety of numerical modeling tools has been applied while trying to understand these unsteady, two-phase flow conditions. A wide variety of modeling strategies has been created to date and, associated with this models, various mathematical formulations were proposed to describe such flows. These range from a simple system of ordinary differential equations, passing through systems of one-dimensional partial differential equations, all the way into Navier-Stokes equations associated with a free surface flow tracking algorithm. There has been limited discussion on the merits, advantages, and limitations of each approach. This manuscript provides a preliminary survey of alternatives to represent unsteady, two-phase flows in urban water systems, with a focus here in one-dimensional formulations. This is a part of a concerted effort of the EWRI Task Committee on Unsteady Two-phase Flows in Urban Water Systems to provide designers with better guidelines to include in their projects the effects of air in the hydraulics of these water systems.