Sedov-Taylor self-similar blastwave

What you are seeing: a strong point explosion releases energy $E$ into a uniform medium of density $\rho_1$. The blast wave expands self-similarly: $R(t) = \xi_0 (E t^2 / \rho_1)^{1/5}$. Post-shock density is exactly $4\rho_1$ for $\gamma = 5/3$.