Feedback from reservoir sedimentation on the flow pattern in rectangular basins

in 6th International Conference on Scour and Erosion (ICSE) (2012, August)

Despite simple geometries, flow in shallow rectangular reservoirs show complex recirculation patterns, which strongly influence the sediment deposits and, in practice, affect the operation and maintenance ... [more ▼]

Despite simple geometries, flow in shallow rectangular reservoirs show complex recirculation patterns, which strongly influence the sediment deposits and, in practice, affect the operation and maintenance costs of such facilities. Based on composite modelling, this research characterizes flow and sedimentation patterns in geometric conditions which have not been investigated so far. Velocity fields developing in rectangular shallow reservoirs (h = 0.2 m) with different asymmetric locations of the inlet and the outlet channels were experimentally investigated. Tests were performed in a reservoir geometry (4.5 m x 4 m) characterized by a stable symmetric flow pattern in the basic symmetric configuration, at constant hydraulic conditions; the aim was to evaluate exclusively the effect of channels displacing on the flow patterns and on the sedimentation of suspended solids. Horizontal velocity components were measured by ultrasound velocity profilers in the entire reservoir and maps of velocity vectors were obtained. Velocity measurements were performed both with clear water and with an inflowing suspended load. At the end of the experiments sediments deposits thickness on the entire reservoir bottom was measured by a laser light method, and maps of sediments deposits thickness were produced. Reservoir trapping efficiency was evaluated, but no significant influence of inlet and outlet channels location on trapping efficiency was observed. Numerical simulations were performed with the depth-averaged model WOLF 2D, in order to assess the ability of the model to reproduce the different types of flow patterns found in the experiments. In particular, a sensitivity analysis on bottom roughness as well as on the turbulence closure model and parameter was performed, in order to analyze a possible feedback effect of sediment deposits and/or suspended load on the type of flow pattern. [less ▲]

A naming convention for the Piano Key Weirs geometrical parameters

in Erpicum, Sébastien; Laugier, Frédérique; Boillat, Jean-Louis (Eds.) et al Labyrinth and Piano Key Weirs - PKW 2011 (2011)

Flood management is more than ever an issue for dam designers and engineering consulting firms in charge of rehabilitation works. Piano Key Weirs are a new cost-effective type of spillway designed to ... [more ▼]

Flood management is more than ever an issue for dam designers and engineering consulting firms in charge of rehabilitation works. Piano Key Weirs are a new cost-effective type of spillway designed to improve dams discharge capacity. These structures are particularly attractive: they can easily be built on existing structures and enable very high discharge capacities. Therefore, Piano Key Weirs are nowadays studied worldwide. Piano Key Weir description involves a lot of geometrical parameters (more than 30), which designations are not already universally defined. A naming convention is required to enhance exchanges and cooperation between the numerous developers. A naming convention has been developed at EDF – Hydro Engineering Center in cooperation with the Laboratory of Hydraulic Constructions (LCH), Ecole Polytechnique Fédérale de Lausanne and the Laboratory of Hydrology, Applied Hydrodynamics and Hydraulic Constructions (HACH), University of Liege. This paper describes the proposed naming convention and gives definitions and notations of the various geometrical parameters. This work represents a first attempt which should be updated with the contribution of stakeholders involved in this topic. [less ▲]

Flow in shallow rectangular basins: experimental study and 2D numerical simulations

in Proc. 8th International Conference on Hydro-Science and Engineering (ICHE) (2008)

Quasi 2D-numerical model of aerated flow over stepped chutes

in Proc. 30th IAHR Congress (2003)

Aerated flow over stepped chutes is principally studied on laboratory models. Consequently, the obtained design relations have a limited field of application. In order to propose a more general ... [more ▼]

Aerated flow over stepped chutes is principally studied on laboratory models. Consequently, the obtained design relations have a limited field of application. In order to propose a more general description of the flow, a quasi-2D numerical model is developed. The fluid is considered as an air-water mixture governed by the shallow-water equations. Moreover, a transport equation for air concentration represents the self-aeration of the flow and a coefficient of uneven vertical velocity distribution integrates indirectly the turbulent structures. The paper includes a brief description of the flow behaviour, the quasi-2D model equations, and a comparison of the numerical results with the measured flow characteristics in a 30° stepped flume. [less ▲]

Génération et transfert des crues extrêmes : le modèle FAITOU

Book published by EPFL - Communications du Laboratoire de Constructions Hydrauliques - Ecole Polytechnique Fédérale de Lausanne (EPFL), Ed. A. Schleiss (2002)

An original physically based hydrological approach for extreme flood computations on digitalized watersheds

in Envirosoft 2000 (2000)

New approach in modelling floods over steep river basins

in 2nd Inter-Regional Conference on Environment-Water (1999)