  E. M. Purcell showed that a body has to perform non-reciprocal motion in
order to propel itself in a highly viscous environment. The swimmer with one
degree of freedom is bound to do reciprocal motion, whereby the center of mass
of the swimmer will not be able to propel itself due to the Scallop theorem. In
the present study, we are proposing a new artificial swimmer called the one
hinge swimmer. Here we will show that flexibility plays a crucial role in the
breakdown of Scallop theorem in the case of one-hinge swimmer or
two-dimensional scallop at low Reynolds number. To model a one-hinge artificial
swimmer, we use bead spring model for two arms joined by a hinge with bending
potential for the arms in order to make them semi-flexible. The fluid is
simulated using a particle based mesoscopic simulation method called the
multi-particle collision dynamics with Anderson thermostat. Here we show that
when our swimmer has rigid arms, the center of mass of the swimmer is not able
to propel itself as expected from the Scallop theorem. When we introduce
flexibility in the arms, the time reversal symmetry breaks in the case of the
one-hinged swimmer without the presence of a head contrary to the one-armed
super paramagnetic swimmer which required a passive head in order to swim. The
reduced velocity of the swimmer is studied using a range of parameters like
flexibility, beating frequency and the amplitude of the beat, where we obtain
similar scaling as that of the one-armed super paramagnetic swimmer. We also
calculate the dimensionless Sperm number for the swimmer and we get the maximum
velocity when the Sperm number is around 1.7.
