Author(s): Abdellah Ghenaim, Yi Liu, Abdelali Terfous, Pierre-Andre Garambois
Linked Author(s): Abdellah Ghenaim
Keywords: Storm sewers, sediment tank, sediment transport, sediment deposition, numerical simulation
Abstract: With the increase of urbanization worldwide, it is crucial to sustainably manage sediment flows in urban networks and especially in stormwater detention basins. One key aspect is to propose optimized designs for detention tanks in order to best reduce flood peak flows and in the meantime to settle particles. It is therefore necessary to understand the complex flows patterns and sediment deposition conditions in stormwater detention basins. The aim of this paper is to study the flow structure and particle deposition pattern for a given tank geometry in view to control and maximize sediment deposition. As a matter of facts, numerical modelling is a useful tool to investigate those complex flow structures. The approach presented here is based on the resolution of the Reynolds averaged Navier Stokes equations to account for turbulent effects and also a passive particle transport model. Given the difficulty involved in those modellings, especially with regard to complex and variables velocity fields and the few existing models for sediment deposition conditions, the choice is made here to test a simple parallelepiped geometry. An analysis of particle deposition conditions is presented in this paper in terms of flow velocities and turbulence patterns. Then sediment deposition zones are presented thanks to the modelling with particle tracking method. It is shown that two recirculation zones seem to significantly influence sediment deposition. Due to the possible overestimation of particle trap efficiency with standard wall functions and stick conditions, further investigations seem required for basal boundary conditions based on turbulent kinetic energy and shear stress. As the trap conditions neglect the resuspension of the particles, a new boundary condition based on shield curves was implemented to the simulation, which can promote the prediction of the trap efficiency and particle distribution zone
Year: 2017