Author(s): Hubert Chanson
Linked Author(s): Hubert Chanson
Keywords: Turbulence; Tidal bores; Physical modelling; Bed roughness; Bore front; Wave attenuation; Turbulent mixing; Sediment processes; Ecology
Abstract: A positive surge results from a sudden change in flow that increases the depth, and a geophysical application is the tidal bore. Mew experimental investigations were conducted in a rectangular channel and detailed unsteady velocity measurements were performed with high temporal and spatial resolution. The experiments encompassed undular and breaking bores in a horizontal slope and both smooth and rough invert conditions were tested. An undular bore was observed for surge Froude numbers less than 1.5. For Fr 1.5, a breaking bore was observed. Detailed instantaneous velocity measurements showed a marked effect of the surge front passage. A comparison between undular and weak surge data suggested some basic differences. A systematic comparison was conducted to study the effects of bed roughness. The boundary friction contributed to some wave attenuation and dispersion. The instantaneous velocity data indicated a marked effect of the rough screens on the entire turbulent velocity field.
Year: 2009