Associate Professor Tallinn University of Technology
The study explains the dynamics of air-water stratified flow in the water collection system with restricted ventilation. The fluids (e.g., air and water) are coupled in the sewer pipe not only by pressure but also due to drag, and thus, the fluid flow can reveal mixed-flow dynamics because of the breaking of an interface. Because of more frequent heavy rainfall, overloading of large-scale combined sewer for gravity-driven flow may result in polluted air bursts from network vent towers. How urban residents olfactory experience urban environments are important for recreation, welfare, and other important shares of human life. Climate change may negatively affect the urban smellscape, which may lead to a new type of air pollution, that has not found much attention due to its complicated nature. Severe storms due to increased rainwater volumes in cities are deepening also management issues of urban infrastructure. Stratified flow in pipe may be influenced by various factors such limited gradient and hence low flow rate, connection to well, pumping station, siphon connection, etc. Water dynamics in the water collection system can be reasonably well gained by the hydraulic models, but modeling of system ventilation is more problematic. The air-water interactions in the particular water collection system with restricted ventilation are explored through the use of 3D numerical model. This study analyses the air-circulation process qualitatively in the water collection system with air-water stratified flow through a computational fluid dynamics model using the open-source software. The air exchange that is associated with the water collection system specific in- an outflow cases are under focus. The case study demonstrates the ability of the advanced numerical modelling tool to predict of air-water interfacial drag and associated air burst of the water collection system, which is ventilated trough several openings.
