  The steady-state simplified $P_N$ approximation to the radiative transport
equation has been successfully applied to many problems involving radiation.
Recently, time-dependent simplified $P_N$ equations have been derived by an
asymptotic analysis similar to the asymptotic derivation of the steady-state
$SP_N$ equations \cite{FraKlaLarYas07}. In this paper, we present computational
results for the time-dependent $SP_N$ equations in two dimensions, obtained by
using an adaptive finite element approach. Several numerical comparisons with
other existing models are shown.
