Experiments and numerical modeling of baffle configuration effects on the performance of sedimentation tanks

Abstract

The hydraulic efficiency of sedimentation basins is reduced by short-circuiting, circulation zones and bottom particle-laden jets. Baffles are used to improve the sediment tank performance. In this study, laboratory experiments were used to examine the hydrodynamics of several baffle configurations. An accompanying numerical analysis was performed based on the 2-D Reynolds-averaged Navier–Stokes equations along with the k-ε turbulence closure model. The numerical model was supplemented with the volume-of-fluid technique, and the advection–diffusion equation to simulate the dynamics of particle-laden flow. Model predictions compared well with the experimental data. An empirical function was constructed to indicate the location and amount of sediment collected in the tank. Hydraulic performance was determined for given baffle locations and heights. The results revealed that, for the laboratory setup, a baffle half way along its length decreases its performance, while a baffle much closer to its inlet and with height 25∼30% of water depth improves efficiency.