A CFD-Based Digital Framework for Scaling Optimization of Orbital Rocking Bioreactors

Robust scale-up of bioreactor systems requires hydrodynamic similarity across scales to ensure consistent cell culture performance. This study presents a computational fluid dynamics (CFD)-guided digital framework for optimizing the scale-up of a novel orbital rocking bioreactor, CELBIC, from CELBIC5 (working volume 1-2 L) to CELBIC50 (working volume 10-20 L). Using lattice Boltzmann-based simulations, key hydrodynamic parameters, including velocity, shear stress, and energy dissipation rate, were evaluated across various working volumes, inclination angles, and agitation speeds. Compared with conventional scale-up criteria, such as average P/V, we propose a comprehensive and digitalized scale-up optimization framework: a root mean square error (RMSE)-based method comparing the full spatial and temporal distributions of various CFD variables to quantify similarities among scaled-up conditions. This approach allows identification of the best-matching scaled-up condition and further refinement using response surface analysis. The optimized condition (10 L, 7°, and 19 rpm) exhibited the lowest combined RMSE relative to the reference condition (CELBIC5 at 1 L, 6°, and 30 rpm), suggesting substantial hydrodynamic equivalence. Overall, this study demonstrates how integrating CFD- and RMSE-based analyses enables rational scale-up of orbital rocking bioreactors, offering a systematic strategy for digital process development in single-use systems.