Development of an efficient CFD-simulation method to optimize the structure parameters of an airlift sonobioreactor

A two-dimensional CFD model was developed for optimizing the structure design of an airlift sonobioreactor for hairy root culture, and a height to diameter ratio of 4 was found suitable for hairy root culture because both oxygen interphase mass transfer rate and liquid flow rate were high in the whole culture process. The installation position of ultrasound transducers was optimized with the help of CFD simulation, the ultrasound transducers set at three layers around the bioreactor wall gave the highest TKE value, turbulent dissipation rate and liquid flow rate among all installation positions tested, which is positive for the dissolved oxygen mass transfer into the center of hairy root clumps. The optimized structure of the airlift sonobioreactor provided great mass transfer performance and sharply reduced the gradient of dissolved oxygen in root domain. The detection results of dissolved oxygen concentration in hairy root clumps before and after ultrasound stimulation proved that ultrasound could enhance the mass transfer of dissolved oxygen into root clumps, which is an advantage for hairy root growth and secondary metabolite accumulation.

► A CFD model with the dynamic mesh method was developed for sonobioreactor design.
► The hydrodynamic parameters change with the bioreactor structure and position of ultrasound transducer.
► CFD simulation provides a powerful means for understanding fluid field in sonobioreactor.