BioMembrOS_Deliverable_3_1

This deliverable presents a comprehensive analysis of oxygen (O2) and carbon dioxide (CO2) transfer in hollow fiber membranes, focusing on optimizing fiber geometry and flow configurations to enhance mass transfer. The study uses Computational Fluid Dynamics (CFD) simulations to explore the effects of different fiber shapes under transverse and parallel flow configurations, including cylindrical and sinusoidal designs. Key geometrical parameters such as amplitude, rotational orientation, and fiber twisting are investigated to understand their influence on gas exchange performance. The results reveal sinusoidal fibers with complex surface structures can theoretically offer higher mass transfer due to a larger gas transfer area. However, they may also introduce flow disturbances that negatively impact mass transfer rates, especially at high Péclet numbers (Pe) where convective transport is dominant. For the investigated singular and multi-fiber models, the findings indicate that cylindrical fibers generally exhibit superior specific (per mass transfer area) O2 uptake and CO2 removal compared to sinusoidal fibers, highlighting the importance of streamlined geometry in optimizing gas transfer in high Pe flows. Additionally, the study shows that the interplay between fiber shape and flow configuration is crucial for achieving superior mass transfer. This research provides valuable insights into fiber design considerations for artificial lungs and blood oxygenators, emphasizing the need for a tailored approach to maximize the efficiency of gas exchange processes. The results from multi-fiber models demonstrate that sinusoidal fibers significantly improve overall gas transfer rates compared to cylindrical fibers, with sinusoidal 4 fibers showing the highest gains. In the 100-fiber model, the total gas transfer rate increases by 6.85% for O2 uptake and 6.16% for CO2 removal, highlighting the potential of larger fiber arrays to enhance gas exchange. Although sinusoidal fibers exhibit lower specific gas transfer values than cylindrical fibers, their higher total gas transfer rate suggests that, with proper optimization of fiber design and spatial arrangement, they can outperform cylindrical fibers in total gas transfer rate. Furthermore, exploring alternative flow configurations, such as diagonal flow with an angle of attack, could further improve gas exchange by promoting better fluid mixing and reducing stagnation zones. These findings point to sinusoidal fibers as a promising solution for enhancing ECMO system performance when combined with optimized flow dynamics.