Author(s): Janek Laanearu

Linked Author(s): Janek Laanearu

Keywords: Ir-water interaction; Hydraulic system; Numerical modelling; Pollution; Climate Change

Abstract: The dynamics of air-water stratified flow through a branched pipe with variable diameters and lengths is numerically analyzed. The air-circulation process in a large-scale pipe with realistic diameters is investigated for the different water-filling flow rates. The Manning formula is used to determine the normal water-flow-ratedependent depth in the sewer pipes. The air and water can be coupled in the water-collection system, in terms of pressure and drag, thus, the air ventilation can occur. The non-mixing flow conditions with a more-or-less stable interface between the air and water is used to numerically demonstrate the airflow patterns through manholes during the water-filling process. The sewer airflow analysis is needed to perform an odor study; the present work gives some insight into the complexity of airflow dynamics in a poorly vented sewer. The air inflow and outflow situations may be relevant for outdoor air quality analysis in urban environment. For this purpose, the 3D numerical model, representing the two-phase flow of immiscible fluids, is used. The numerical model flow regime is chosen to be turbulent, and the air and water phases are considered to be incompressible, isothermal and Newtonian fluids. Interface tracking for the air-water flow is resolved by applying the volume of fluid method. The air exchange associated with branched pipe stratified-flow regimes are presented, i. e., unsteady and uniform flow conditions. The case study demonstrates the ability of the advanced numerical modeling tool to predict air-water interfacial drag and associated air exchange of the collector, which is ventilated through several venting towers.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0353-cd

Year: 2023