Presenter: Alex Chamolly, Ph.D., Unversity of Cambridge
Topic: Propulsion, navigation, and control of biological and artificial microswimmers
In this talk, I will describe some of the topics that I have worked on in my Ph.D. with Prof. Eric Lauga at the University of Cambridge. I will begin by presenting a minimal theoretical model of flagellar bundle formation for peritrichous bacteria that allows us to analyze the relative contribution of the many mechanisms that contribute to this complicated elastohydrodynamic problem. Using this model we demonstrate that under very general conditions the bundle formation is governed by flows that are indirectly generated by cell body translation. Following this I will talk about some numerical work concerning the motion of a general squirmer microswimmer through a periodic three-dimensional lattice of obstacles, modeling a porous medium such as soil. We observe qualitatively different trajectories depending on the squirming parameter and the lattice packing density and rationalize our results with theoretical near- and far-field hydrodynamic arguments. Turning the attention towards artificial microswimmers, I will then talk about the stochastic dynamics of a dissolving active particle. Starting with two different dissolution models, we predict the lifetime and mean squared displacement of such colloids as functions of many experimentally accessible parameters, and infer fundamental limitations of their controllability. Finally, if there is time, I will conclude with a discussion of a hydrodynamic trapping effect, allowing a spheroidal roller to transport cargo particles along with an interface. We predict this effect numerically using finite element simulations and explain it theoretically in analogy with the well-established microfluidic mechanism of deterministic lateral displacement.