Assessing Flow Rate through a Lake Siphon System via Computational Flow Modeling

Siphons are often used to release excess water from impoundments such as lakes. They eliminate the use of pumps, which save energy and provide consistent water level control. However, it is often difficult to determine the actual flow rate at different stages of a siphon cycle. Field condition, storm type, and design criteria play critical roles in major and minor loss components of an active siphon system. A calibrated model thus can be useful to evaluate the performance of a siphon. Therefore, the objective of this study is to estimate the flow rate through a lake siphon system via three-dimensional modeling. Spencer Creek Lake in West Tennessee is chosen for this study, which is monitored by a water level sensor at the lake and another near the siphon outlet. The lake level data are simulated in the Ansys-Fluent package for steady flow conditions at various stages of the siphon operation. It reveals the associated flow physics of the siphon operation. Therefore, sources of loss at different sections of the siphon system can be identified to correlate with the discharge. Finally, the predicted outlet discharge is compared to the flow rate at the outlet channel. The successful calibration of the siphon system would allow the lake operators to estimate siphon release at different stages of an active siphon cycle and provide the knowledge to design more effective siphons for other lakes in West Tennessee.