EFFECT OF VORTEX BREAKDOWN ON MASS TRANSFER IN A CELL CULTURE BIOREACTOR

Abstract

The present work shows that vortex breakdown may also occur in a bioreactor for animal cell or tissue culture. The aim is to study the effect of vortex breakdown on the fluid environment for cell growth, particularly hydrodynamic stress and mass transfer. A numerical simulation of the fluid flow and oxygen transfer in a cylindrical bioreactor is presented, in which a rotating base wall is used to generate the medium flow and mixing. The steady and laminar, axisymmetric Navier-Stokes and species equations are solved by the numerical model based on finite volume method. The hydrodynamic stress and oxygen transfer conditions are systematically studied by varying the two key parameters which determine the flow behavior: bioreactor aspect ratio H/R and a rotation Reynolds number Re=ΩR2/ν. It is found that the oxygen concentration at the attached breakdown vortex center is significantly higher than that at the main recirculation center but the hydrodynamic stress level is almost similar in the two regions. The results would provide guidance on choosing the proper operating parameters for cell or tissue culture.