Author(s): E. C. Jamieson; C. D. Rennie; R. D. Townsend
Linked Author(s):
Keywords: Turbulence; Vorticity; Local scour; Groynes; Laboratory experiment; Coherent structures
Abstract: Detailed measurements of the unique 3-D patterns of velocity, turbulence and bed morphology associated with flow in a channel bend with a series of stream barbs (upstream-pointing submerged groynes) have been carried out in a mobile-bed laboratory channel. The submerged nature of these structures creates a unique combination of flow separation at the barb tips and overtopping (plunging) flow conditions, causing 3-D eddies of various scales to form. Quantifying the influence of this highly 3-D and complex flow field on a mobile sand bed provides new and valuable data for understanding the impact and performance of these structures. Densely-spaced velocity data collected in the vicinity of the barbs indicate a correspondence between the calculated vorticity field, turbulent stresses and the location of coherent structures with the scour holes at the barb tip. These results provide new insight into possible connections between vorticity, coherent structures, turbulence and local scour phenomena.
Year: 2011