Evolution of the angular velocity as a function of time for the reference models. Plotted on the left as the rotational periods in days and during the right as the angular velocity in solar units with Ω_⊙ = 2.86 × 10^-6 s^-1. Each cross represents a measurement for a star belonging to an open cluster whose age has been taken from the literature. All observational data are taken from Gallet & Bouvier (2015, and references therein) except the “OD” black frame between 8 and 10 Gyr, which corresponds to photometric data for stars observed with the Kepler satellite that belong to the disc of the Milky Way (McQuillan et al. 2013). Solid lines show the evolution of surface rotation for the slow (magenta), medium (green), and fast (blue) rotating models, while short dashed lines represent the associated averaged angular velocity of the radiative interior.