Numerical simulations, scaling analysis, surrogate experiments, and analytical model of the dynamics of microorganisms under creeping flow in a rotating bioreactor

The indefinite suspension of cells in culture media is an important factor in their growth as well as their viability. The rotating wall vessel (RWV) is a culture vessel that was designed to create laminar flow and continuous suspension of cells in the vessel. In this work, the dynamics of the particles that are suspended inside an RWV were investigated. An analytical solution for the position of a particle in an unbounded flow was derived and compared to experimental and simulation results. A simulation scheme that utilizes Stokesian dynamics under conditions of creeping flow was used to model the hydrodynamic interactions between the particles and the wall. The orbits that were formed by the particle depend on a dimensionless Rayleigh number, and these orbits were grouped into four categories: Pure Solid-Body Rotation, Distorted Resuspension, Wall Interaction, and Pure Sedimentation.