  Previously, we developed a late time approximation scheme to study the
interior geometry of black holes. In the present paper we test this scheme with
numerical relativity simulations. In particular, we present numerical
relativity simulations of the interior geometry of charged spherically
symmetric two-sided black holes with a spacelike singularity at $r = 0$. Our
numerics are in excellent agreement with the late time approximation. We also
demonstrate that the geometry near $r = 0$ is a scalarized Kasner geometry and
compute the associated Kasner exponents.
