Evolution of the core relaxation time, τ_rc(t) in the units of τ_rh(t), calculated from Eq. (11). The horizontal axis shows time in terms of the initial half-mass relaxation time, τ_rh(0). The left-hand set of panels is for the 10k-* clusters, the right-hand set is for 50k-*. The models are separated by the primordial binary star numbers and masses (columns), the binary star initial semi-major axes (colours), and the initial cluster half-mass radius (line styles). Each line is averaged over all realisations of the corresponding model.