Numerical Modeling of Flow Field in Three Types of Vortex Settling Basins

Vortex settling basins (VSBs) are efficient and economical structures that use free-surface vortex strength to remove sediment particles from flow. In this study, computational fluid dynamics was employed to predict and evaluate the effects of basin geometry on performance and flow field structure. The flow field was calculated using Reynolds-averaged Navier-Stokes modeling and large eddy simulation. Verification of the numerical simulations was carried out based on experimental data obtained using a typical VSB model. The Smagorinsky model results for abstraction ratio, velocity component, and free-surface flow were superior to those of the other turbulence models. The distinctive features of two previously proposed designs for vortex settling basins were investigated, and a new geometry to enhance these features is presented. The results indicated that the new geometry provided better performance in generating a symmetric central vortex, lengthening the particle settling path and decreasing the abstraction ratio. (C) 2021 American Society of Civil Engineers.