Simulation of effect of a baffle on the flow patterns and hydraulic efficiency in a sedimentation tank

Abstract

This paper is concerned with a solid–liquid two-phase model combining with the k–ε turbulent model for the numerical simulation of the effect of a baffle on the hydraulic characteristics and solid removing rate of a sedimentation tank. The computed flow patterns, the distributions of solid concentration along vertical lines on the cross sections were obtained in the sedimentation tank by numerical simulation. Comparisons of the computed results show that: (1) with the horizontal baffle-distance between 0.5 and 2.5 m, the removal rate increases with a decrease in the horizontal baffle-distance, and ranges from 82.63 to 92.6%. Therefore, the horizontal baffle-distance between 0.5 and 2 m is recommended, (2) with an increase of baffle submerged-depth from 0.5 to 2 m, the removal rate at outlet increases, and especially, with the baffle-depth from 0.5 to 1 m, the removal rate increases obviously; however, with the baffle submerged-depth from 2 to 2.5 m, the removal rate decreases slightly, which shows that the baffle does not need a much greater submerged-depth, and 2 m is recommended. The research results can provide a useful reference for the design of sedimentation tanks.