Prediction of Mean and Turbulent Kinetic Energy In Rectangular Shallow Reservoirs

Abstract

Shallow rectangular reservoirs are common structures in urban hydraulics and river engineering. Despite their simple geometries, complex symmetric and asymmetric flow fields develop in such reservoirs, depending on their expansion ratio and length-to-width ratio. The original contribution of this study is the analysis of the kinetic energy content of the mean flow, based on UVP velocity measurements carried throughout the reservoir in eleven different geometric configurations. A new relationship is derived between the specific mean kinetic energy and the reservoir shape factor. For most considered geometric configurations, leading to four different flow patterns, the experimentally observed flow fields and mean kinetic energy contents are successfully reproduced by an operational numerical model based on the depth-averaged flow equations and a two-length-scale k- turbulence closure. The analysis also highlights the better performance of this depth-averaged k- model compared to an algebraic turbulence model. Finally, the turbulent kinetic energy in the reservoir is derived from the experimental measurements and the corresponding numerical predictions based on the k- model agree satisfactorily in the main jet but not in the recirculation zones.