  In hydrodynamical modeling of the ultrarelativistic heavy-ion collisions the
freeze-out is typically performed at a constant temperature or density. In this
work we apply a dynamical freeze-out criterion, which compares the
hydrodynamical expansion rate with the pion scattering rate. Recently many
calculations have been done using event-by-event hydrodynamics where the
initial density profile fluctuates from event to event. In these event-by-event
calculations the expansion rate fluctuates strongly as well, and thus it is
interesting to check how the dynamical freeze-out changes hadron distributions
with respect to the constant temperature freeze-out. We present hadron spectra
and elliptic flow calculated using (2+1)-dimensional ideal hydrodynamics, and
show the differences between constant temperature and dynamical freeze-out
criteria. We find that the differences caused by different freeze-out criteria
are small in all studied cases.
