Author(s): Jin-Hua Si; Siow-Yong Lim; Xi-Kun Wang

Linked Author(s):

Keywords: Jet-flipping; Local scour; Particle image velocimetry; Apron; Plunging jet

Abstract: An apron is a common measure to mitigate the scouring of a river bed caused by a plunging jet overflowing an unsubmerged weir; the apron changes the interactions between the river bed and the flow structures compared to a no-apron case. Moreover, the presence of an apron can cause the jet-flipping phenomenon under certain hydraulic conditions. This paper uses Particle Image Velocimetry (PIV) to measure the transient flow structures of jet-flipping. The results show that four types of roller (large-scale vortices) are identified, and that the scouring of the river bed is mainly caused by the ‘major roller’ while the refilling process is tightly related to the ‘bed roller’. Furthermore, the study investigated the temporal development of the scour hole with the cyclical jet-flipping behaviour.

DOI: https://doi.org/10.3850/978-981-11-2731-1_067-cd

Year: 2018