Author(s): M. H. Omid; A. R. Habibzadeh
Linked Author(s):
Keywords: Resistance; Bedload roughness; Supercritical flow
Abstract: Movement of sediment particles along the bed in subcritical flow produces additional roughness to that without sediment transport. The magnitude of this bed load roughness is proportional to the thickness of the sediment layer moving along the bed, the particle size and the sediment concentration. In the case of supercritical flow, however, further resistance is expected due to momentum absorption of high flow velocity. In this study the effect of sediment movement on flow resistance in supercritical flow was experimentally investigated. The experiments consisted of creating supercritical flow conditions carrying sediment by injecting fine gravel (D50=5. 42mm) into the flow in a rigid rectangular channel. Sediment was injected at the upstream at a rate just to produce bedload transport without any deposition. Sediment concentration was increased progressively by increasing the injection rate of sediment into the flow stream. The results show that the friction factor in supercritical flow is significantly increased as the sediment concentration along the bed is increased.
Year: 2007