Computational Fluid Dynamics, service reservoir, water quality, flushing time, inlet configuration
Service reservoirs provide the dual function of balancing supply with demand and providing adequate pressure in the water supply network by maintaining sufficient pressure head. In a potable water service reservoir, the flushing time is a major water quality concern due to the potential loss of chlorine residual. The flushing time is closely related to the flow pattern in the reservoir. In this study, the influence of change of water inlet configuration and baffling on flushing time was examined Multiphase computational fluid dynamics (CFD) was used to simulate service conditions and predict flow patterns. To determine the flushing time, two identical fluids with the properties of water were used in the simulation with one fluid in the reservoir initially and the other fluid introduced through the inlet. The volume fraction of the initial fluid at the ideal flushing time was used to determine the effects of inlet configuration and baffling. A laboratory scale model was used to validate results produced from the CFD model. In the physical model, a saline solution was used as the initial fluid in the reservoir and fresh water was introduced through the inlet. A time series of the conductivity of the solution was measured at a specific point and was compared to a volume fraction monitor point in the numerical simulation to validate results. Four different scenarios were assessed with different inlet configurations and locations including a baffle wall located near the inlet to direct the flow.
The authors of this paper extend their appreciation to National University of Ireland, Galway, Ward and Burke Construction Ltd., and Irish Centre for High End Computing (ICHEC). Special thanks are also given to Sean Cranney and Jerry Lin.