Mean divergence, $\overline{d(\mathbf{x})}$, of the baryonic velocity field as a function of dark matter density. For a spatial location x, there exists the correspondence between the divergence, d(x) = ∇⋅u(x), of baryonic velocity field (u) and the dark matter density, ${\mathrm{\Delta }}_{\mathrm{dm}}(\mathbf{x})={\rho }_{\mathrm{dm}}(\mathbf{x})/{\overline{\rho }}_{\mathrm{dm}}$. For a density interval centered at Δ_dm, we counted all the points within this interval, which enabled us to calculate the mean value of d(x). Throughout the paper, we use an overbar to indicate a statistically averaged quantity.