The gasdynamics of fission-fragment heating

The transient motion of a gas heated in a spatially nonuniform fashion by fission fragments is considered. Comparisons of an analytical solution for the one-dimensional Cartesian problem and numerical simulations of the Euler equations using the Flux-Corrected Transport (FCT) method indicate that the choices of the diffusion coefficients which yield sixth-order- or fourth-order-accurate versions of FCT are not optimal for this problem. A hybrid method using diffusion coefficients lying between the values of the above versions requires an order-of-magnitude fewer grid points to reproduce the analytical solution. Representative numerical simulations are presented to illustrate the different effects that Cartesian and axisymmetric geometries have on the gas motion. Numerical simulations of experiments with two-dimensional effects are compared to experimental pressure measurements