Virginia Tech™home

Fluid mechanics of the respiratory system and active coating materials

Wednesday, March 31, 2021

2:30–3:45 pm

Zoom meeting here (email Dr. Domann for passcode)

Arnold Mathijssen

Departments of Physics and of Astronomy

University of Pennsylvania


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.


Arnold Mathijssen was named ‘30 under 30’ by Scientific American and was awarded the Sir Sam Edwards PhD Thesis Prize for his work in group of Julia Yeomans FRS at the University Oxford (2016). Supported by an HFSP crossdisciplinary fellowship, he moved to the lab of Manu Prakash at Stanford University, where the American Physical Society presented him the Charles Kittel Award (2019). He is now Assistant Professor of Physics & Astronomy at UPenn, and guest editor of Physics of Fluids for a special issue on Kitchen Flows – you are invited to contribute!