  In this letter, we report results on the effect of temperature variations on
a granular assembly through Molecular Dynamic simulations of a 2D granular
column. Periodic dilation of the grains are shown to perfectly mimic such
thermal cycling, and allows to rationalize the link between the compaction
process, the local grains dynamics and finite size effects. Here we show that
the individual grain properties, namely their roughness and elastic modulus
define a minimal cycling amplitude of temperature \Delta Tc below which the
dynamics is intermittent and spatially heterogeneous while confined into
localized regions recently coined "hot spot" [Amon et al., Phys. Rev. Lett.
108, 135502 (2012)]. Above \Delta Tc, the whole column flows while the grains
dynamics ranges continuously from cage-like at the bottom of the column to
purely diffusive at the top. Our results provide a solid framework for the
futur use of thermal cycling as an alternate driving method for soft glassy
materials.
