A computational fluid dynamics study on the optimisation of a circular sedimentation tank using perforated inlet baffles

A numerical study on a circular sedimentation tank was done to investigate the effect of perforated inlet baffles on the efficiency and performance of the sedimentation tank. Three new modified geometries with perforated baffles placed at strategic locations in the inlet region were studied and compared with the original sedimentation tank that contains an ordinary stilling well and a McKinney baffle. The Euler-Lagrange approach of multiphase modelling was employed in this study using the Discrete Phase Model. The numerical model employed in this study was validated using experimental data from the literature. It was observed that the perforated baffles are effective in dissipating the kinetic energy in the inlet region and also help in producing a more distributed and tranquil flow in the settling region. Of the four cases studied, case-4 was found to be the most efficient, with 58.36% total settling efficiency, which is an increase of 10.96% from that of the original tank. However, it was also found that case-3 can also be considered a viable option for the retrofitting project if a slight compromise in performance enhancement could be tolerated in exchange for a more efficient utilisation of the added materials. Comparisons of the different cases studied have also been conducted through assessments like settling efficiencies, velocity magnitude contours, turbulence kinetic energy contours, and particle trajectories obtained through numerical simulations.