Aspects of flagellate motility: individuals, simplifications, and populations.

Eamonn Gaffney

Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford

Flagella are ubiquitous slender appendages that function as microbiological fluid actuators in diverse settings, enabling sperm swimming and egg transport in mammalian reproduction, the virulence of numerous parasitic pathogens and bacterial swimming. In this talk we examine various aspects of motility of individual cells, demonstrating that simple mechanics can explain diverse observations of how cells respond to fluid flow. We ubiquitously also observe Jeffrey’s orbit dynamics in shear flows, and such behaviours are subsequently explored theoretically and simplified using multiple scale asymptotics. We then proceed to discuss to consider populations of swimmers, both in terms of rationally simplifying models of individual swimmers for upscaling, which also highlights the perils of not using systematic techniques for averaging. We finish by exploring how data from populations of swimmers can be exploited for hypothesis testing, which may also find application in characterising population variation for large scale population simulations of swimmers.