Discrete elements method of neutral particle transport. Doctoral thesis

Technical Report · Sat Oct 01 04:00:00 EDT 1983

OSTI ID:6746039

Mathews, K A

A new 'discrete elements' (LN) transport method is derived and compared to the discrete ordinates SN method, theoretically and by numerical experimentation. The discrete elements method is more accurate than discrete ordinates and strongly ameliorates ray effects for the practical problems studied. The discrete elements method is shown to be more cost effective in terms of execution time with comparable storage to attain the same accuracy, for a one-dimensional test case using linear characteristic spatial quadrature. In a two-dimensional test case, a vacuum duct in a shield, LN is more consistently convergent toward a Monte Carlo benchmark solution than SN, using step characteristic spatial quadrature. An analysis of the interaction of angular and spatial quadrature in xy-geometry indicates the desirability of using linear characteristic spatial quadrature with the LN method. The discrete elements method is based on discretizing the Boltzmann equation over a set of elements of angle. The zeroth and first angular moments of the directional flux, over each element, are estimated by numerical quadrature and yield a flux-weighted average streaming direction for the element. (Data for this estimation are fluxes in fixed directions calculated as in SN.)

• Research Organization: Air Force Inst. of Tech., Wright-Patterson AFB, OH (USA). School of Engineering
• OSTI ID: 6746039
• Report Number(s): AD-A-138080/7; AFIT/DS/PH-83-5
• Country of Publication: United States
• Language: English

Related Subjects

654003* -- Radiation & Shielding Physics-- Neutron Interactions with Matter
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALGORITHMS
BOLTZMANN EQUATION
CARTESIAN COORDINATES
COORDINATES
DIFFERENTIAL EQUATIONS
DISCRETE ORDINATE METHOD
EQUATIONS
MATHEMATICAL LOGIC
NEUTRON TRANSPORT THEORY
PARTIAL DIFFERENTIAL EQUATIONS
TRANSPORT THEORY