Numerical simulation of additional guiding baffles to improve velocity distribution in an oxidation ditch

Abstract

AbstractThe effect of guiding baffles downstream from surface aerators on the flow fields in an oxidation ditch (OD) was studied using an experimentally validated numerical tool, based on computational fluid dynamics (CFD) model. The two-phase gas–liquid model and the 3D RNG k-e turbulence model were used to describe flow motion in ODs. The algorithm of pressure-implicit with splitting of operators (PISO) was used to solve velocity and pressure. The volume of fluid (VOF) method was used to simulate free water surface. Comparisons of the velocity distributions under the two conditions (with and without guiding baffles) show that the installed guiding baffles downstream from the surface aerators can increase the velocity at the ditch bottom, and the vertical velocity distributions in the OD become more uniform, which will help to prevent sludge deposit at the bottom of an OD and have an obvious effect on time prolongation for liquid–gas mixture.