Resolving two-body hydrodynamic interactions between microswimmers

The squirmer model is a canonical model for spherical microswimmers (e.g., ciliated microorganisms and Janus particles) in Stokes flow, where propulsion is driven by a surface slip velocity. Due to its simplicity and versatility, the squirmer model is a popular tool for modelling the collective dynamics of microswimmers. While the flow field of a single squirmer in an infinite fluid domain is fully resolved, our knowledge on the hydrodynamic interactions between a pair of squirmers at all separations is still incomplete. This will become important in dynamic simulations of suspensions of microswimmers, such as Stokesian Dynamics. In this work, we use a boundary collocation method to resolve the hydrodynamics of a pair of squirmers with high efficiency and accuracy. Ultimately, this method permits investigation of systems involving non-spherical microswimmers at a range of length scales, from single-particle to collective dynamics.