  Radiation flow through an inhomogeneous medium is critical in a wide range of
physics and astronomy applications from transport across cloud layers on the
earth to the propagation of supernova blast-waves producing UV and X-ray
emission in supernovae. This paper reviews the current state of the art in the
modeling of inhomogeneous radiation transport, subgrid models developed to
capture this often-unresolved physics, and the experiments designed to improve
our understanding of these models. We present a series of detailed simulations
(both single-clump and multi-clump conditions) probing the dependence on the
physical properties of the radiation front (e.g. radiation energy) and material
characteristics (specific heat, opacity, clump densities). Unless the radiation
pressure is high, the clumps will heat and then expand, effectively cutting off
the radiation flow. The expanding winds can also produce shocks that generates
high energy emission. We compare our detailed simulations with some of the
current subgrid prescriptions, identifying some of the limitations of these
current models.
