Comparison of various turbulence model performance in computational fluid dynamics analyses of the oxidation ditches with experimental validation

Experimental and numerical studies were carried out to determine the full-scale Oxidation Ditch (OD) hydrodynamics considering various turbulence models. Firstly, the experimental work was carried out in a full-scale plant by Acoustic Doppler Velocimeter (ADV) for field-measurements. Secondly, the experimental data was used to validate numerical models by using Computational Fluid Dynamics (CFD) software Ansys Fluent. Eight different turbulence models were compared in the numerical study to predict full-scale hydrodynamics. Results showed that standard k-ε, renormalization group k-ε, realizable k-ε turbulence models gave more accurate prediction results with relative errors of 13 %, 17 %, and 18 % respectively, whereas the standard k-ω turbulence model gave the worst prediction results with 39 % relative error. This study also shows that the velocities in the ODs are very low without external force such as air diffusers, rotors, and mixer and there is no homogeneous flow field distribution in the ODs. Moreover, the maximum wastewater velocities occurred at the inlet and outlet.