Abstract
AbstractAlthough computational fluid dynamics (CFD) modelling has been applied to study bioprocesses where mechanical mixing and aerations are key, the effect of having a free surface has usually been ignored. This work studies a mixing tank for bioprocess applications to analyze the impact that the assumption of a flat liquid level has upon the modelling results, with and without aeration. The methodology takes an experimental and modelling approach. A dual impeller mixer with a speed of 400 rpm is used for batch systems with both non‐Newtonian and Newtonian fluids to characterize the axis torque and surface vortex formation. Several multi‐phase CFD models are applied to study the modelling and numerical effects of the headspace on the results. Regarding modelling accuracy, the CFD models are shown to be able to capture the effect of the free surface on the fluid dynamics of the stirred tank for different fluid rheologies. Therefore, the simplification of the liquid level as a flat and fixed surface should not be applied, especially for a process with aeration or when unaerated conditions can lead to a surface vortex. Regarding the numerical accuracy, it is concluded that the mixture model does not predict the interface shape as well as the Eulerian model. However, only the mixture model shows to be numerically stable. Overall, this work provides validated CFD configurations able to predict the effect of a free surface on the mixing mechanisms in stirred reactors.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.