Streaming Effects and Collision Probabilities in Lattices

AbstractIn a previous publication by Benoist, a simple and general formulation of the streaming effect in lattices was established which defines the diffusion coefficients by a suitable weighting of the mean-free-paths of the various media; this formulation introduced special types of collision probabilities initially calculated by an iteration technique. However, it appeared better to work with a closed formulation as the series of angular correlation terms evidenced a very slow convergence, especially for large channels. This approach requires the solution of the Boltzmann equation with particular types of sources.This solution is shown to be equivalent to the treatment of a cell in terms of some fictitious reaction. rates which are defined. The problem is essentially analogous to the calculation of the thermal utilization factor, an analogy that has been exploited as far as possible. Finally, by an adjustment on the corresponding void channel system, the treatment of fueled channels is made and a new m...