Vortex configurations and spin-down curves for different pinning strengths V₀. Top: grey-scale plots of the final (t = 1000) superfluid density for V_i = 0, 8.3, 16.6 and 33.7 (left to right, respectively). The density grey-scale runs from dark (low density) to light (high density). Bottom: angular velocity of the crust as a function of time Ω(t) for V_i = 0, 8.3, 16.6 and 33.7 (solid, dotted, dashed and dot–dashed, respectively). Simulation parameters: η = 1, ΔV_i/V₀ = 0.0, R = 12.5, Δx = 0.15, Δt = 5 × 10⁻⁴, N_EM/I_c = 10⁻³, Ω(t = 0) = 0.8, n_pin/n_F = 0.97, Δt_sm = 1.0.