CFD Modeling of Two-Phase Stirred Bioreaction Systems: Applications of Large-Eddy-Simulation (LES) Simulation

A novel Euler-Lagrange approach for performing three-dimensional CFD simulations of bioreactors and fermenters is presented. This approach, which is based on the Lattice-Boltzmann model (LBM), eliminates the manual grid meshing process associated with CFD and runs orders-of-magnitude faster than conventional modeling tools. Since the LBM approach conserves energy, it provides direct access to the energy dissipation rates and turbulent energy spectrum at arbitrary points across within the domain. Moreover, owing to the explicit time-integration of the flow field, the time-evolution of scalar fields, bubble fields, and reactions can be tracked in tandem with the flow field solution.

In this work, we apply the LES approach to simulate the time-evolution of product, substrate and dissolved oxygen through exploring Monod/Contois type bioreaction kinetics models previously published in literature. Full transient simulations have been attempted through accounting for Kla and viscosity variations as a function of viscosity and biomass concentration respectively. Computational results are compared against the available experimental data published in the literature. The key benefits of using the Euler-Lagrange approach over a conventional Euler-Euler framework includes reduced simulation run-times, and generality of the applied physics, which appeals to standard literature correlations with no manual parameter tuning.