Author(s): Sameh Kantoush
Linked Author(s):
Keywords: Flow pattern; Rectangular reservoir geometry; Shallow flow; Symmetric; Asymmetric; Suspended sediment transport
Abstract: Recirculating flows in shallow rectangular reservoir with different shape were investigated in order to study the effect of geometry. Experimental tests have been conducted in a rectangular shallow basin of 4m width by varying systematically its length from 6, 5, 4, to 3 m (length to width ratio of 1. 5, 1. 25, 1 and 0. 75) and its width from 4, 3, 2, 1 to 0. 5 m (length to width ratio of 1. 5, 2, 3, 6 and 12) for a constant length of 6 m. The water depth and discharge were kept similar for all experiments. For all these geometries, measurements have been performed of the reattachment length of a separated flow. These pointed out the influence of geometry and sediment deposits on the large scale turbulence coherent structures. Large Scale Particle Image Velocimetry (LSPIV) was used for a detailed description of the velocity field of the asymmetric flow that form in symmetric, 2D plane and shallow reservoir geometries. The flow and boundary conditions that gave rise to asymmetric flow are presented. Asymmetric flow structures were observed starting from shape ratios ≥ 1. 5. By decreasing the reservoir length below a shape ratio < 1. 5, the flow structure generally tends towards a symmetric pattern. Furthermore the location of the reattachment zone and its flow structure determine the local transport properties of the flow. Experiments have been carried out not only with clear water but also with suspended sediment transport.
Year: 2007