  Hydrodynamic interactions are crucial for determining the cooperative
behavior of microswimmers at low Reynolds numbers. Here we provide a
comprehensive analysis of the scaling and strength of the interactions in the
case of a pair of three-sphere swimmers with intrinsic elasticity. Both
stroke-based and force-based microswimmers are analyzed using an analytic
perturbative approach. Following a detailed analysis of the passive
interactions, as well as active translations and rotations, we find that the
mapping between the stroke-based and force-based swimmers is only possible in a
low driving frequency regime where the characteristic time scale is smaller
than the viscous one. Furthermore, we find that for swimmers separated by up to
hundreds of swimmer lengths, swimming in pairs speeds up the self propulsion,
due to the dominant quadrupolar hydrodynamic interactions. Finally, we find
that the long term behavior of the swimmers, while sensitive to initial
relative positioning, does not depend on the pusher or puller nature of the
swimmer.
