Examination of three-dimensional flow characteristics in the distribution channel to the flocculation basin using computational fluid dynamics simulation

This study was conducted to evaluate the equity of the flow distribution from the rapid mixing basins to the flocculation basins. Several types of inlet structure of the open channel affecting the flow pattern and distribution trend were simulated using the computational fluid dynamics (CFD) technique. In order to investigate the factual phenomena in the distribution channel, we selected a certain domestic water treatment plant with capacity of 361,000 m³ d⁻¹. From the results of CFD simulation and measurements of flow discharge, it was investigated that the existing inlet geometry resulted in significant inequitable distribution. The largest deviations of flowrate in the basins and rows were both over 10%. In order to reduce these deviations, this study suggested installing a baffle against the influent, and the largest deviation was reduced to less than 3%. It was concluded that the existing design method of the open channel could be improved by optimizing the even flow with three-dimensional hydrodynamic analysis.