Affiliation - University of Pennsylvania
Title of Talk - Fluid mechanics of the respiratory system and active coating materials
Our airways are continuously exposed to potentially harmful particles like dust and viruses. The first line of defence against these pathogens is a network of millions of cilia, whip-like organelles that pump flows by beating over a thousand times per minute. In this talk, I will first discuss the connection between local ciliary architecture and the topology of the flows they generate. We image the mouse airway from the sub-cellular (nm) to the organ scales (mm), characterising quantitatively its ciliary arrangement and the resulting flows. Interestingly, we find that disorder in the ciliary alignment can actually be beneficial for this pathogen clearance . Second, I would also like to discuss how systems can be driven out of equilibrium by such active carpets. Combining techniques from statistical and fluid mechanics, I will demonstrate how we can derive the diffusivity of particles near an active carpet, and how we can generalise Fick’s laws to describe their non-equilibrium transport . These results may be used for designing self-cleaning materials, much like our airways.  Ramirez San-Juan, Mathijssen et al., “Multi-scale spatial heterogeneity enhances particle clearance in airway ciliary arrays”, Nature Physics 16, 958–964 (2020)  Guzman-Lastra, Löwen & Mathijssen, “Active carpets drive non-equilibrium diffusion and enhanced molecular fluxes”, in press, Nature Communications (2021) Note: We also have an informal discussion session after the seminar. Please stay in the Zoom seminar room to chat together with Professor Arnold Mathijssen!