Document Type : Research Paper
Civil Engineering Department, Estahban Branch, Islamic Azad University, Estahban, Iran.
Department of Water Engineering, Faculty of Agriculture, Isfahan University of Technology, Isfahan, Iran
The complex interaction between turbulent flow and sediment particles in the bed results in local scour around the bridge pier. Most of the studies are in the field of scour and is less attention to investigation of the flow structure around the pier and in particular the pier with the protective agent. In this study, to investigate of the turbulent flow around a round-nosed rectangular pier with bed sill has been paid by measuring velocity profiles and the contribution of each bursting events to the Reynolds shear stress determined and has been investigated. Three-dimensional velocities of flow in the centerline of the channel were measured using an Acoustic Doppler Velocimeter. The velocity data has been investigated using quadrant analysis to recognize the susceptible regions for sediment entrainment and deposition. The results showed that the sweep event is the dominant phenomenon. Sweep and ejection events have an effective mechanism for sediment entrainment around the pier with bed sill. Investigation the variations |S_(i,H) | with H showed that in downstream of the pier, the contribution of each bursting events to the Reynolds shear stress production due to the presence of bed sill are weaker into the pier upstream.