Author(s): Macdonald; Cooker; Bacon; Alexander
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Keywords: No Keywords
Abstract: This study was designed to improve understanding of water and sediment movement around channel floor obstacles such as boulders in river beds.A hemisphere secured to the floor of a flume acted as a simple obstacle, and the flow over it was controlled to generate a hydraulic jump due to local acceleration over the downstream half of the hemisphere. The motion of water and sediment was observed. Previous studies have investigated fluid-dynamical character of flows around hemispheres (Schlichting, 1936; Taneda, 1956), the associated erosion of prepared sediment beds (Werner et al., 1980), the resistance to flow caused by in-stream structures (Morris, 1959), and have related the experimental flow character to associated microhabitats for fish (Franca et al., 2009). In previous flume studies, flows around isolated hemispheres have been subcritical everywhere in the flow-space and only Best and Brayshaw (1985) examined the fate of sediment added to a flume during a run.
Year: 2009