The Lattice Boltzmann Method applied to linear particle transport

Abstract

In this study, the applicability of the Lattice Boltzmann Method to neutron transport is investigated. The transport model used, is derived from the Boltzmann equation for neutral particles by inverting the streaming operator and casting the integral transport equation into an operator form. From the operator equation, an iterative solution to the transport problem is presented, with the first collision source as the starting point for the iteration scheme. One of the main features of the method is the simultaneous discretization of the phase space of the problem, whereby particles are restricted to move on a lattice. A full description of the discretization scheme is given along with the iterative procedure and quadrature set used for the angular discretization. To mitigate lattice ray effects, an angular refinement scheme is introduced to increase the angular coverage of the problem phase space. The method is then applied to a model problem to investigate its applicability to neutron transport. Three cases are considered where constant, linear and exponential interpolants are used to account for the accumulation of flux due to the streaming of particles between nodes. The results obtained are compared to a reference solution, that was calculated by using the MCNP code and to the values calculated using a nodal SN method. Finally, areas of improvement are identified and possible extensions to the algorithm are provided.