Author(s): Nazanin Khezri; Hubert Chanson
Linked Author(s): Hubert Chanson
Keywords: Tidal bores; Bed load; Transient sheet flow; Turbulence; Physical modelling
Abstract: A tidal bore is a series of waves propagating upstream in a river mouth as the tide starts rising. The transient sediment motion beneath a breaking bore was investigated by measuring simultaneously the fluid and sediment motion in laboratory. Although there was no sediment transport observed during the initially steady flow, a transient sediment sheet flow motion was observed beneath the breaking bore. The sediment transport was initiated during the passage of the roller toe, when the discontinuity of the free-surface slope induced a large longitudinal pressure gradient force. The particles were subjected to large horizontal accelerations, with between 5 and 10% of all particles being subjected to maximum accelerations larger than 1 g. The particles were advected upstream with an average velocity close to the instantaneous fluid velocity. The present data provided some quantitative data in terms of various force terms acting on sediment particles beneath a tidal bore.
Year: 2013