3D simulation on four design methods of water distribution uniformity for typical peripheral feed sedimentation tank

In order to analyze the uniformity of water distribution for four inflow design methods on peripheral feed sedimentation tank, three-dimensional simulation was carried out by computational fluid dynamics(CFD) technique in a typical sediment tank with diameter 20 m, the uniformities of water and sludge mass flow rates were simulated and compared for four different design methods. The homogeneous sub-model of Eulerian-Eulerian Multiphase Model was adopted in simulation of the tank distribution channel, three phases of water, granular sludge and air(above water) were included, four commonly used design methods in engineering practice-varied-channel-fixed-aperture, varied-channel-varied-aperture, fixed-channel-fixed-aperture and fixed-channel-varied-aperture were selected and simulated. The results showed that none of the four design methods was able to achieve an evenness distribution of water and sludge, which had a minimum 10% of standard deviation of apertures in mass flow rate. The distribution uniformities of water and sludge by varied-channel method were comparatively better and can be employed preferentially. With varied-aperture design method, a very small variation of apertures in diameters was derived, while the distribution evenness of water and sludge were improved obviously with adoption of fixed-channel width method.