  Inspired by the classical Kepler and Rutherford problem, we investigate an
analogous set-up in the context of active microswimmers: the behavior of a
deformable microswimmer in a swirl flow. First we identify new steady bound
states in the swirl flow and analyze their stability. Second we study the
dynamics of a self-propelled swimmer heading towards the vortex center, and we
observe the subsequent capturing and scattering dynamics. We distinguish
between two major types of swimmers, those that tend to elongate
perpendicularly to the propulsion direction and those that pursue a parallel
elongation. While the first ones can get caught by the swirl, the second ones
were always observed to be scattered, which proposes a promising escape
strategy. This offers a route to design artificial microswimmers that show the
desired behavior in complicated flow fields. It should be straightforward to
verify our results in a corresponding quasi-two-dimensional experiment using
self-propelled droplets on water surfaces.
