  The "squirmer model" is a classical hydrodynamic model for the motion of
interfacially-driven microswimmers, such as self-phoretic colloids or volvocine
green algae. To date, most studies using the squirmer model have considered
spherical particles with axisymmetric distribution of surface slip. Here, we
develop a general approach to the pairing and scattering dynamics of two
spheroidal squirmers. We assume that the direction of motion of the squirmers
is restricted to a plane, which is approximately realized in many experimental
systems. In the framework of an analytically tractable kinetic model, we
predict that, for identical squirmers, an immotile "head-to-head" configuration
is stable only when the particles have oblate shape and a non-axisymmetric
distribution of surface slip. We also obtain conditions for stability of a
motile "head-to-tail" configuration: for instance, the two particles must have
unequal self-propulsion velocities. Our analytical predictions are compared
against detailed numerical calculations obtained using the boundary element
method.
