a)–c): period, damping time, and damping ratio as a function of the length of the thread for thread models with l/a = 0.2 and for two values of the density contrast. d) − f): the same quantities for thread models with ρ_f/ρ_c = 200 and for three values of the transverse inhomogeneity length-scale. In all figures a = 1, R_m = 10⁶, ρ_ev = ρ_c, and l_z = a. Times are shown in units of the internal filament Alfvén crossing time, τ_Af = a/v_Af. Symbols correspond to fully numerical 2D computations while the different line styles represent the approximate 2D solutions obtained by Soler et al. (2010). All computations have been performed in a two-dimensional grid with N_r = 401 and N_z = 51 points, with 250 grid-points in the resonant layer. Lengths are normalised to a = 1 and L = 50a.