Study of hydrodynamic stress in cell culture bioreactors via lattice-Boltzmann CFD simulations supported by micro-probe shear stress method

Mammalian cell cultivation in pharmaceutical industry can last up to units of weeks and requires proper transport of nutrients and oxygen for cell growth and production. Given the long time period, cells experience flow fields from all bioreactor's zones, where the energy dissipation rate (ε) varies substantially. Shear sensitive micro-probes with size comparable to cells and Kolmogorov eddies are used for the determination of the maximum hydrodynamic stress (τmax) in bioreactors. For the very first time, the micro-probe method is applied successfully not only to laboratory (3 L) and pilot scale (80 L and 200 L), but also to industrial production scale bioreactor (12,500 L) with Rushton turbine and pitched-blade (RT-PB) impeller configuration. Experimentally obtained data are used for the validation of comprehensive CFD scale-up study, using the Lattice-Boltzmann large eddy simulation (LB-LES) method. Besides τmax, this work also focuses on the study of mixing time and flow field attributes.