  We investigate the hydrodynamic interaction between two elastic swimmers
which are composed of three spheres and two harmonic springs. In this model,
the natural length of each spring is assumed to undergo a prescribed cyclic
change, representing internal states of the swimmer [K. Yasuda et al., J. Phys.
Soc. Jpn. 86, 093801 (2017)]. We obtain the average velocities of two identical
elastic swimmers as a function of the distance between them both for
structurally asymmetric and symmetric swimmers. We show that the mean velocity
of the two swimmers is always smaller than that of a single elastic swimmer.
The swimming state of two swimmers can be either bound or unbound depending on
the relative phase difference between the two elastic swimmers.
