Author(s): Youkai Li, Hubert Chanson
Linked Author(s): Youkai Li
Keywords: Decelerating bores, physical modelling, arrested hydraulic jump, ensemble-averaging.
Abstract: A tidal bore is a hydraulic jump in translation occurring in the estuarine zone where the river has a funnel-shaped mouth. For a decelerating bore propagating upstream against a steep slope, its properties vary at different locations before it finally changes into an arrested bore: i. e. a stationary hydraulic jump. The present study conducted some novel and systematic research on the transformation of a decelerating bore into a stationary hydraulic jump in a relatively large channel with adverse slope. The arrested bore could be of different types: an undular jump with long shock waves, strong secondary waves and no breaking, a partially breaking jump with long shock waves and strong secondary waves, or a strongly breaking jump with short shock waves and weak secondary waves. All the experiments were repeated more than 25 times to yield some ensemble-averaged results in terms of the free-surface characteristics, velocity and turbulent Reynolds stresses. Physically, the decelerating bore propagation induced maximum free-surface and velocity fluctuations associated with the bore front passage, but there was a time lag between the occurrence of the maximum fluctuations, hinting some coupling effect between the free-surface elevations and turbulent velocity during the decelerating bore passage
Year: 2017