LAUSR

ABSTRACT The approximate 1D model for particle transport in ducts that is based on the use of two basis functions to represent the transverse and azimuthal-angle dependencies of the angular flux is applied to the case of a duct of rectangular cross section. Isotropic particle incidence is considered. Numerical results obtained for the reflection and transmission probabilities from the 1D models with one and two basis functions are compared with Monte Carlo results for the full 3D problem. It is shown that the 1D model with two basis functions performs very well for ducts of rectangular cross section, displaying deviations of less than 3% with respect to Monte Carlo, in general. Two exceptions in the general behavior of this model are very short ducts, for which deviations in the reflection probability of up to 9% in magnitude were encountered, and long ducts with strongly absorbing walls, for which the deviations in the transmission probability reached about 8% in magnitude.