Development of Multi-Frequency Multi-Scale Radiation Transport Modeling

The objective of this proposal is to develop advanced radiation transport modeling techniques that accurately and efficiently treat transport in media having widely varying optical properties; in particular, hot gases and plasmas with optical depths ranging from the optically thin to the optically thick regimes. In doing this, we will develop a hybrid diffusion-Monte Carlo (HDMC) model that efficiently transports multi-frequency radiation on multi-dimensional grids. During Phase I, we will perform initial development of the HDMC software, and demonstrate its accuracy and efficiency on simple 1-D grids. Also in Phase I, we will: study the potential for utilizing variance reduction methods for improving efficiency, investigate the use of escape probability techniques to more accurately treat the transport of line radiation, and develop plans for implementing efficient domain decomposition techniques for 3-D grids. Modeling techniques developed during Phase I will be extended to support simulations on 2-D and 3-D grids during Phase II. The new models will be benchmarked against known solutions, and will be tested for efficiency and scalability to many-processor systems. Successful completion of this work will result in an efficient multi-scale multi-dimensional radiation transport package that accurately treats radiation flow in materials with realistic frequency-dependent radiative properties.