Scale-up analysis of geometrically dissimilar single-use bioreactors.

Cell culture scale-up is a challenging task due to the simultaneous change of multiple hydrodynamic process characteristics and their different dependencies on the bioreactor size as well as variation in the requirements of individual cell lines. Conventionally, the volumetric power input is the most common parameter to select the impeller speed for scale-up, however, it is well reported that this approach fails when there are huge differences in bioreactor scales. In this study, different scale-up criteria are evaluated.

Quantifying the hydrodynamic stress for bioprocesses.

Hydrodynamic stress is an influential physical parameter for various bioprocesses, affecting the performance and viability of the living organisms. However, different approaches are in use in various computational and experimental studies to calculate this parameter (including its normal and shear subcomponents) from velocity fields without a consensus on which one is the most representative of its effect on living cells. In this letter, we investigate these different methods with clear definitions and provide our suggested approach which relies on the principal stress values providing a maximal distinction between the shear and normal components.

Numerical and Experimental Investigation of the Hydrodynamics in the Single-Use Bioreactor Mobius CellReady 3 L.

Two-way Euler-Lagrange simulations are performed to characterize the hydrodynamics in the single-use bioreactor Mobius CellReady 3 L. The hydrodynamics in stirred tank bioreactors are frequently modeled with the Euler-Euler approach, which cannot capture the trajectories of single bubbles. The present study employs the two-way coupled Euler-Lagrange approach, which accounts for the individual bubble trajectories through Langrangian equations and considers their impact on the Eulerian liquid phase equations.

CFD-Based and Experimental Hydrodynamic Characterization of the Single-Use Bioreactor Xcellerex XDR-10.

Understanding the hydrodynamic conditions in bioreactors is of utmost importance for the selection of operating conditions during cell culture process development. In the present study, the two-phase flow in the lab-scale single-use bioreactor XcellerexTM XDR-10 is characterized for working volumes from 4.5 L to 10 L, impeller speeds from 40 rpm to 360 rpm, and sparging with two different microporous spargers at rates from 0.

Simulation of patient-specific bi-directional pulsating nasal aerosol dispersion and deposition with clockwise 45° and 90° nosepieces.

Numerical simulations of the dispersion and deposition of poly-disperse particles in a patient-specific human nasal configuration are performed. Computed tomography (CT) images are used to create a realistic configuration of the nasal cavity and paranasal sinuses. The OpenFOAM software is used to perform unsteady Large Eddy Simulations (LES) with the dynamic sub-grid scale Smagorinsky model.

Large eddy simulation of the flow pattern in an idealized mouth-throat under unsteady inspiration flow conditions.

An excellent understanding of the airflow properties is critical to improve the drug delivery efficiency via the extrathoracic airway. The present numerical study focuses on the investigation the characteristics of important airflow structures such as the secondary vortices, the impinging jet and the recirculation zone under unsteady inspiration flow conditions in a circular idealized mouth-throat model using large eddy simulation (LES). Five inhalation cycles are simulated, the last one of which is analyzed in detail at five different times.

Numerical study of the airflow structures in an idealized mouth-throat under light and heavy breathing intensities using large eddy simulation.

An excellent understanding of the airflow structures is critical to enhance the efficiency of drug delivery via the human oral airway. The present paper investigates the characteristics of both steady and unsteady airflow structures in an idealized mouth-throat using large eddy simulation (LES). Representative inhalation flow rates of 15L/min at rest and 60L/min in exercise are considered.