Numerical evaluation of the low Reynolds turbulent flow behaviour in a bioreactor

Bioreactors are commonly used in industry, owing to their low energy requirement. These reactors are often operated at reduced flow rates in order to maintain a high retention time, and reduce shear stress on the biomass. An important factor is the mixing between biomass and substrate, and thus the maintenance of turbulence is important. Hence, the aim of this work is the application of the CFD technique to obtain a better understanding of the turbulent behaviour in an anaerobic sequencing batch reactor, with a nominal Reynolds number of about 1,700. This study considered a single-phase approach to evaluate several turbulence models. The obtained results indicate that the flow has little influence on the regions in the transition regime for the conditions evaluated, in spite of the low Reynolds number. Moreover, comparing the use of different models, it was found that the Reynolds stress model does not require longer time for its calculations.