Computational fluid dynamics as a modern tool for engineering characterization of bioreactors
Since design, construction and evaluation of bioreactors for large-scale production is costly and time consuming, computational methods may give some insights into the fluid mechanics within bioreactors. Thus, critical limiting factors, such as insufficient mixing as well as inhomogeneous nutrient and oxygen mass transfer, may be identified early in the design process. Although advanced experimental techniques such as laser Doppler anemometry and particle image velocimetry are also reliable, they are too time consuming to characterize the complete flow pattern in industrial scales and rely on optical accessibility. Therefore, the knowledge of flow characteristics provided by computational fluid dynamics (CFD) is indispensable for the rational design of bioreactors. Based on previously published reviews, the present work summarizes the latest publications on the usage of CFD to characterize and scale-up bioreactors used in biotechnological processes. Selected models that are used to predict the fluid flow pattern and key engineering parameters of commonly used bioreactors are described. Related issues, such as grid dependency of CFD results and the requirement for experimental verification are also addressed. Finally, an overview of proposed but not yet feasible CFD applications is presented, including fluid–structure interaction, the use of direct numerical simulation and the coupling fluid flow and chemical reactions.