Direct and inverse energy cascades in strongly rotating turbulent flows*

\\ Rotation plays a key role in many geophysical and astrophysical flows. Under a strong rotation rate (low Rossby numbers), three-dimensional turbulent flows show a tendency to develop fluctuations in a plane perpendicular to the rotation axis leading to a two-dimensional and three-components (2D3C) evolution. By using high resolution direct numerical simulations up to $4096^3$ collocation points we present a systematic analysis of the 2D3C field and of the energy transport both concerning direct and inverse cascades using a decomposition in helical-Fourier modes.