Author(s): A. Parvaresh Rizi; S. Kouchakzadeh; M. H. Omid
Linked Author(s): Salah Kouchakzadeh
Keywords: Transcritical Flow; Unsteady Flow; Boundary Conditions; Moving Hydraulic Jump
Abstract: The occurrence of transcritical or mixed flow, i. e. supercritical and subcritical flow regimes, is considered as a special case in unsteady flow in a channel reach which can clearly be exemplified by a moving hydraulic jump. Some complexity is inherent in the numerical analysis of transcritical flow and published experimental data regarding this kind of flow are scarce. In this research an experimental setup was prepared to compile the hydraulic characteristics of transcritical flow in a rectangular flume. The flume was equipped with a sluice gate at the upstream boundary. Each inflow hydrograph generated unsteady supercritical flow regime at the downstream side of the sluice gate and formed a moving hydraulic jump along the channel. During each run the flow depth behind the gate was continuously recorded by transducer and the water surface profile along the channel was recorded by using a video recorder. Based on the recorded data, some flow parameters such as flow depth, pressure head and energy head were determined. The result reveals specific relations between the discharge and moving hydraulic jump parameters. Also, by applying proper assumptions and employing steady state momentum and energy equations simple and time independent relations were obtained, that determines the pressure head in subcritical region of unsteady mixed flow. Consequently, having the discharge variation as upstream boundary condition, one may reliably estimate the unsteady transcritical flow parameter based on time independent relations.
Year: 2005