Kink wave transverse velocity (v_x) at the loop centre (x = y = 0) as a function of altitude and time. The velocity is shown for four 3D simulations with different driver periods P₀, after an initial settling time of 2P₀ (for P₀ = 200 s, 335 s, and 700 s), or 0.42P₀ (for P₀ = 2000 s). The dashed black lines represent a propagation at the kink speed (see Eq. (13)), and are independent of the driver period.