ZHANGShi-hao,AIHeng-yu,CUIWan-ying,et al.Evaluation Indicators of Flocculation Performance Based on CFD Simulation[J].China Water & Wastewater,2022,38(5):45-53.
Evaluation Indicators of Flocculation Performance Based on CFD Simulation
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第38卷
Number:
第5期
Page:
45-53
Column:
Date of publication:
2022-03-01
- Keywords:
- computational fluid dynamics（CFD）; flocculation performance; evaluation indicator; turbulence; velocity gradient
- Abstract:
- Traditional evaluation indicators of flocculation performance is only an overall evaluation of the flocculation process, and lacks accurate description of the flocculation process, so it is not suitable to be used as the indicators for flocculation performance evaluation simulated by computational fluid dynamics (CFD) software. Based on the dynamic process and flow characteristics of flocculation, the applicability of five evaluation indicators in CFD simulation of flocculation process was discussed from the aspects of hydrodynamics and flocculation morphology. The growth scale and density of flocs depended on vortex velocity gradient G’, and Euler number Eu determined the perfection of the flocculation process. When the overall flow field was investigated, the flocculation process could be evaluated more accurately by using both local G’ and Eu. Turbulent kinetic energy k and turbulent energy dissipation rate ε should also be introduced to investigate the relationship between energy input and flocculation performance. When evaluating the effective vortex generating capacity of flocculating equipment, the eddy scale λ could be indirectly calculated by using the flow field parameters obtained from post?processing and used as the evaluation indicator, and the uniformity of velocity distribution γv should also be considered to investigate the uniformity of vortex distribution. When the morphology of flocs was used as the evaluation indicator, CFD model should be combined with population equilibrium model (PBM) to establish a PBM-CFD coupling form to solve the problem.
Last Update:
2022-03-01