Figure 4.

Correlation of direction of motion between cells. (A–C) Direction of velocity vector v_i/|v_i| for each cell represented by arrows for different ratios of the polarity alignment strength to the polarity noise intensity κ_φ/D_φ. For illustration, small square domains (12 × 12) of a system are shown. (D) Dependence of the cross correlation C of unit velocity vector v_i/|v_i| defined by Eq. 8 on the distance between cells r for the different values of κ_φ/D_φ. (E) Dependence of the average velocity order parameter 〈Φ〉 in Eq. 6 on the ratio κ_φ/D_φ. Arrows point to κ_φ/D_φ = 0 (red), 1.6 (green), and 3.2 (blue). The solid circles indicate the steady-state values of 〈Φ〉. (F) Dependence of the average velocity modulus 〈v〉_i on κ_φ/D_φ. Error bars indicate the SD. (G) Velocity autocorrelation C_a for different values of κ_φ/D_φ. In all panels, L = 24, N = 800, v₀ = 1.2, μ = 10, and D_φ = 0.5 in Eqs. 1–3. To see this figure in color, go online.