The proposed study seeks to increase the fundamental understanding of the local effects of shear and turbulence on cell growth and productivity. The experimental technique will involve measurement of fluid velocity, shear stress, and turbulent intensity in standard Bellco bioreactors with a Laser-Dappler Anemometry (LDA) system. Velocity and turbulence mappings as a function of vessel height and radial distance will be determined over a wide range of operating conditions and vessel sizes. LDA measurements will be done in reactors containing a medium analogue fluid that simulates the fluid environment of cultured cells. Effects of hydrodynamic forces on the cells will be evaluated using standard cell loading, cell growth rate, oxygen uptake and product concentration measurements. Data collected will then be used to develop a quantitiative model correlating hydrodynamic properties with cell growth, metabolism and productivity. LDA measurements, as proposed in this study, are thought to allow for more accurate correlations to be made in bioreactors where a high degree of non- uniform turbulence occurs.
