Fig. 4. Experimental results and comparison to theory and simulations.

a Cell sheet image overlaid with PIV arrows, and best fit length scale ξ_T. b Experimental Fourier velocity correlation function normalised by mean velocity (dots), and best fit to theory with a single stiffness parameter ${\xi }_T^2=\mu \tau ∕\zeta$. c Experimental real-space velocity correlation function (dots) and theoretical prediction. d Velocity autocorrelation function for the experiments, theoretical predictions for different τ, and simulation results for the same soft disk and SPV model simulations as in f. e Mean velocity magnitude for the experiments, and the soft disk, dividing soft disk and SPV model simulations. f Numerical results for soft, soft dividing, and SPV model interactions (solid lines), and theoretical predictions (dashed lines) for the same τ = 2.5h, $k=55{\mu }_m^{-2}{h}^{-1}$ and v₀ = 90 μmh⁻¹ (see text). g Normalized velocity distribution from experiment (black with grey confidence interval), and the three simulated models.