FLUID-DYNAMICS IN BUBBLE-COLUMN BIOREACTORS - EXPERIMENTS AND NUMERICAL SIMULATIONS

Detailed measurements of multiphase flows that prevail in bioreactors tell us that different transport mechanisms are dominating on differen t observation scales. The consequence in terms of reactor modeling is that the processes on different scales can be treated independently. A three-dimensional, dynamical model is presented that can be used to d escribe bubble column bioreactors on the reactor scale. It is based on the Navier-Stokes equation system. On the next smaller scale, the dyn amics of the gas phase is described in a Lagrangian way, by tracking m any bubble clusters or bubbles simultaneously on their way through the reactor. The model is capable of describing bubble columns of differe nt size and can thus be used for scale-up. Its performance is demonstr ated with a production-scale beer fermenter. (C) 1996 John Wiley & Son s, Inc.