Numerical Simulation of Influence of Inlet Configuration on Flow Pattern in Primary Rectangular Sedimentation Tanks

Design of primary settling tank has historically been done more empirically than rationally. The main reason for this is a lack of understanding of what pollutants primary settling tank are capable of removing. Inlets should be designed to dissipate the kinetic energy or velocity head of the mixed liquor. They should be able to distribute the flow equally in vertical and horizontal directions. Inlets should also be designed to prevent short-circuiting. Flow in primary settling tank is simulated by means of computational fluid dynamic (CFD). The fluid is assumed incompressible and non-buoyant. Two-dimensional simulation for one-phase flow has been done. The RNG turbulent model was solved with the Navier-Stockes equations. The flow pattern properties in the settling tank include the velocity profiles, the flow separation area and kinetic energy. In this study, the effect of inlet configurations on these characteristics is considered. Due to this object, rectangular, slope and curved shape of inlet slot are suggested.