Discrete Diffusion Monte Carlo for grey Implicit Monte Carlo simulations.
- Jeffery D.
- Todd J.
- Thomas M.
- Michael W.
Discrete Diffusion Monte Carlo (DDMC) is a hybrid transport-diffusion method for Monte Carlo simulations in diffusive media. In DDMC, particles take discrete steps between spatial cells according to a discretized diffusion equation. Thus, DDMC produces accurate solutions while increasing the efficiency of the Monte Carlo calculation. In this paper, we extend previously developed DDMC techniques in several ways that improve the accuracy and utility of DDMC for grey Implicit Monte Carlo calculations. First, we employ a diffusion equation that is discretized in space but is continuous time. Not only is this methodology theoretically more accurate than temporally discretized DDMC techniques, but it also has the benefit that a particle's time is always known. Thus, there is no ambiguity regarding what time to assign a particle that leaves an optically thick region (where DDMC is used) and begins transporting by standard Monte Carlo in an optically thin region. In addition, we treat particles incident on an optically thick region using the asymptotic diffusion-limit boundary condition. This interface technique can produce accurate solutions even if the incident particles are distributed anisotropically in angle. Finally, we develop a method for estimating radiation momentum deposition during the DDMC simulation. With a set of numerical examples, we demonstrate the accuracy and efficiency of our improved DDMC method.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 977972
- Report Number(s):
- LA-UR-05-3781; TRN: US201012%%599
- Resource Relation:
- Conference: Submitted to: American Nuclear Society Topical Meeting in Mathematics&Computations, Avignon, France, 2005
- Country of Publication:
- United States
- Language:
- English
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