Author(s): Yu Qian; David D. Zhu; Nallamuthu Rajaratnam
Linked Author(s):
Keywords: Air water interaction; Numerical modeling; Sewer systems; Urban hydraulics
Abstract: In present study, a numerical model was built to predict the air requirement in a circular pipe system with changing slopes. A Volume of Fluid (VOF) type free surface model with blending functions on morphologic parameters were adopted and ANSYS CFX-14. 0 was used for the modelling. A corresponding physical experiment was conducted to calibrate the numerical model and verify the accuracy of the numerical model. Water flow rate, air flow rate, water depth upstream and downstream of the jump and air velocity profile in headspace were measured and plotted with numerical modelling outcomes. It is found that the numerical model is able to model the bulk air mass flow rate with hydraulic jump and some of the detailed flow structures can be modeled relatively in good agreement with physical experiments. It is also found that the amount of air entrained into the system is higher than published data. Pressure gradient and the existence of water surface drag may act together on affecting the bulk air flow rate. The present numerical model has the potential in predicting more complicated flow scenarios such as flow with transient water discharge, supercritical water flow etc.
Year: 2015