  Rotating turbulence is an example of a three-dimensional system in which an
inverse cascade of energy, from the small to the large scales, can be formed.
While usually understood as a byproduct of the typical bidimensionalization of
rotating flows, the role of the three-dimensional modes is not completely
comprehended yet. In order to shed light on this issue, we performed direct
numerical simulations of rotating turbulence where the 2D modes falling in the
plane perpendicular to rotation are removed from the dynamical evolution. Our
results show that while the two-dimensional modes are key to the formation of a
stationary inverse cascade, the three-dimensional degrees of freedom play a
non-trivial role in bringing energy to the larger scales also. Furthermore, we
show that this backwards transfer of energy is carried out by the homochiral
channels of the three-dimensional modes.
