Surface transformation of bioactive glass in bioreactors simulating microgravity conditions. Part II: Numerical simulations

The effects of simulated microgravity on the surface modification of bioact ive glass (BG) in solution were studied using a numerical method. Models we re developed for estimating the mass transfers of different chemical specie s from the surface of bioactive glass particles (microcarriers) suspended i n the rotating liquid medium of a NASA-designed high aspect ratio vessel (H ARV) bioreactor and on the bottom surface of a static vial. The concentrati on profiles resulting from chemical reactions and ionic transports were asc ertained. Numerical results for the transport under simulated microgravity in the HARV and at normal gravity in the static vial were compared. These r esults were also compared with those of experiments to verify the enhanceme nt of the reaction kinetics under simulated microgravity conditions. The ex perimental and numerical studies confirm that simulated microgravity condit ions lead to the quick achievement of bioactive glass surface modification. (C) 2001 John Wiley & Sons, Inc.