D-meson nuclear modification factor and v$_2$ in Pb-Pb collisions at the LHC

We present the ALICE results on open heavy flavour, focusing on the exclusive reconstruction of charmed mesons via displaced decay topologies. These measurements benefit from the large Pb-Pb statistics collected in 2011. The results on the nuclear modification factor Raa for D mesons indicate a suppression of their yield in central collisions relative to binary-scaled pp collisions in a large momentum range. The comparison to the Raa of non-prompt J/psi (measured with CMS) indicates a difference in the suppression of charm and beauty, as expected according to the predicted mass hierarchy in energy loss models. The measurement of the azimuthal anisotropy of charmed mesons is also discussed. The observed positive second Fourier harmonic v2 for transverse momentum 2<pT<6 GeV/c in semi-peripheral events is a hint for collective motion of charm quarks. The results discussed above are also compared to theoretical models.