Analytical and numerical studies of the effect of shape on microswimmer propulsion

Abstract

The shape of an active colloid has an enormous effect on the motion of the particle and allows for significantly more variation in its design and application. In this thesis, the dynamics of both convex (spheroidal) and concave (helical and toroidal) particles are investigated with analytical and numerical methods. Starting with an individual particle, it is shown that breaking symmetries of the particle shape can enlarge the possibilities for particle motion, both for self-diffusiophoretic microswimmers and within the more general ``squirmer model''. These results are then extended to include pair interactions. For interacting spheroids, two types of stable pair configurations can exist: co-moving "head-to-tail`` and stationary "head-to-head" pairs. We also consider the interaction of a torus and sphere, with a view towards designing "lock-and-key" interactions.