A set of equations modeling compaction behavior in a two phase mixture of inert granular high explosive and interstitial gas, is discussed and solved numerically in two dimensions. This model treats both phases as compressible, viscous fluids using modified Navier Stokes equations, and standard constitutive relations. One dimensional limits, such as shock tubes and piston-driven problems compare favorably to analytical solutions and experimental data of Sandusky, etal cite{sandlid}, respectively. The model also includes explicit intraphase transfer of mass, momenta, and energy to describe the interactions between the two phases, while at the same time conserving mass, momenta, and energy, and maintaining frame invariance. The equations are then solved using simple two-dimensional extensions of these cases, and the results are compared to the one-dimensional data, with good agreement. Finally, a forcing term, in the form of a concentrated energy source, is used to demonstrate two-dimensional behavior. Compaction is shown to develop in these test problems.