As part of the Multiphase Flows in Bioreactors group, the reasearch of Ryan Rautenbach is centered around the characterisation and study of the scale-up and down of Bioreactors, not only as part of the research group but also as part of the CHOLife+ subproject of the DFG Priority Program SPP2170 "InterZell".

The CHOLife+ initiative is centred on achieving full spatiotemporal resolution of for the characterisation of bioreactors, ranging from small 3L bioreactors to large 15,000L systems. The focus is on advancing the understanding of mixing heterogeneities, flow behaviours and mixing phenomena at various scales through the application of Lagrangian Sensor Particles (LSP) and lattice Boltzmann large eddy simulations (LBS). Multiscale experimental analysis and simulation of lifelines in bioreactors to study their impact on the cultivation performance of Chinese Hamster Ovary (CHO) cells.

Efforts are directed towards mapping and fully characterising stirred-tank reactors (STRs) and respective spatiotemporal gradients, examining the distribution of flow behaviour, and residence times of cells and molecules based on their respective lifelines.

Data from characterisation of the STRs are used for the improved design and operation of scale-down single multi-compartment bioreactor (SMCB). Operated at the University of Stuttgart the SMCB reactor, enables the replication of key hydrodynamic features under laboratory conditions.

The combination of sensor systems such as LSPs, LBS and other methods provide a multi-faceted approach to capture the complete picture of bioreactor performance. This includes studying the transport and mixing efficiency by tracking Lagrangian particles, mimicking the trajectory of cells within the fluid flow.

Additionally, attention is given to the gas-liquid dynamics in multiphase reactors, specifically aiming to quantify gas hold-up and mass transfer rates which are vital for the efficiency of bioprocesses. This research embodies a systematic approach to bioreactor characterization, combining experimental methodologies with computational fluid dynamics to enhance the predictability and scalability of bioprocess outcomes. Through this analytical synergy, the program is setting a new standard for the optimization of bioreactors in the biopharmaceutical industry.

Oral Presentations

• Rautenbach, R.; Hofmann, S.; Buntkiel, L.; Barczyk, J.; Reinecke, S.; Hoffmann, M.; Takors, R.; Hampel, U.; Schlüter, M.: Resolved Particle Lattice-Boltzmann Large Eddy Simulation in a 15,000 L Bioreactor to mimic Lagrangian Sensor Particles,  8th BioProScale Symposium, Berlin, Germany, 2024, oral presentation

Undergraduate and Graduate Teaching Assistant

• Einführung in CAD (winter semester 2023/2024)

• Computational Fluid Dynamics in Process Engineering (summer semester 2024)

Supervised Theses

Current Theses:

• "Lagrangian Trajectory Comparison between Flow-Tracers and Inertial Particles by Means of 4D-PTV", working title, Mustafa Salli, Master thesis, ongoing

• "Measurement of Gas Hold-Up in a 30L Stirred Tank Reactor", working title, Gautama Halim, Bachelor thesis, ongoing

Finished Theses:

• "Documentation & Refinement of the 4D Particle Tracking Velocimetry Setup in the 3 L Stirred Tank Reactor", Mustafa Salli, project work, 2024; documentation can be found here on request