This is a phenomenological study of the interaction between a shock and a separated boundary layer using Large Eddy Simulation (LES). The geometry is the NACA 0012 profile. The computational Mach number is 0.799 and the angle of attack is 2.26 degrees. The simulations are done at different Reynolds numbers, 3·105, 5·105 and 1·106. The subgrid-scale (SGS) effect are accounted for through the inherent dissipation of the numerical algorithm and an anisotropic dynamic divergence subgrid-scale model (DDM). The amplitude and the frequency of the shock movements are reported. It is found that the DDM is too active in the region where the shock is located giving rise to an overestimate of SGS-turbulence. There is a certain periodicity in the shock movements. One of the dominating frequencies is shown to be related to the late stage of the transition process.