Software

The Transport Methods Group is primarily a methods development group that develops both fully functional research codes and special-purpose applications codes. CCS-4 is responsible for the entire spectrum of development, from methods to algorithms to software packages to application support. The following are a few of our current projects.

PARTISN

PARTISN provides neutron transport solutions on orthogonal meshes with adaptive mesh refinement (AMR) in one, two, and three dimensions. A multigroup energy treatment is used in conjunction with the Sn angular approximation. Much effort has been devoted to making PARTISN efficient on massively parallel computers. The package can be coupled to nonlinear multiphysics codes that run for weeks on thousands of processors to finish one simulation. PARTISN's predecessor, DANTSYS has been widely distributed by RSICC to users throughout the world. Regular releases of PARTISN are made available through RSICC.

JAYENNE

The JAYENNE Project is for researching and developing production software for the stochastic nonlinear transport of thermal x-rays. The stochastic transport method is the Implicit Monte Carlo (IMC) method of Fleck and Cummings (JCP, 1971). Some of the features are grey and multigroup frequency treatment and Random Walk (Fleck and Canfield, JCP, 1984) for speeding up the IMC in diffuse regimes. The software is written in object-oriented C++. A levelized, or acyclic, design allows for testing of low level components, which can then be used with confidence by higher level components. This design allows, for example, the same physics software to use multiple meshes, some of which are three-dimensional orthogonal nonuniform structured meshes, two-dimensional RZ Adaptive Mesh Refinement (AMR) meshes, and one-dimensional spherical meshes.

MILAGRO

MILAGRO is a stand-alone code that performs nonlinear radiative transfer calculations using the Fleck and Cummings method of Implicit Monte Carlo (IMC). Milagro is an object-oriented, C++ code that utilizes classes in Draco, CCS-4’s radiation transport library. Milagro and its underlying classes have been significantly upgraded since 1998, when results from Milagro were first presented. Most notably, the object-oriented design has been revised to allow for optimal stand-alone parallel efficiency and rapid integration of new classes. For example, the better design, coupled with stringent component testing, allowed for immediate integration of a full domain decomposition parallel scheme.

WEDGEHOG

WEDGEHOG uses the Implicit Monte Carlo (IMC) technique to solve the thermal radiation transport equation in the x-ray regime on an AMR Eulerian mesh in one-dimension spherical and two-dimension cylindrical geometries. Currently, it is capable of both grey (one energy group) and multigroup transport. This project represents CCS-4’s first effort to create a completely new software package using modern software engineering practices.

ZATHRAS

Zathras solves the time-dependent, three-temperature, grey, flux-limited diffusion, P-1/3, and P-1 radiative transfer equations. It includes material motion corrections, advanced internal linear solvers, and links to external linear solvers (LAMG and BoxMG). It is first-order accurate in time and second-order in space for six geometries on both ratio-zoned and AMR meshes. It is massively parallel via a link to UPS. Zathras was written from scratch in F90/95 utilizing levelization, Design by Contract, unit testing, and other modern software engineering techniques. The build system is based on Draco and automatically builds and runs unit tests on four architectures with seven compilers. It utilizes a flat interface for easy integration with other languages.

CAPSAICIN

The mission of the Capsaicin Project is the development, implementation, and verification of deterministic radiation transport capabilities on unstructured meshes. The Capsaicin team is concentrating its efforts on the development of robust and accurate discretizations of the first-order form of the transport equation. The team is also researching parallel algorithms to improve solution efficiency on massive parallel computers. SERRANO is a software package in the Capsaicin project for solving the time-dependent 3T equations in two-dimension geometries on unstructured triangular meshes.

RESEARCH AND ARCHIVED CODES

ATTILA

Attila solves the three-dimensional multigroup transport equations for neutrons, charged particles, and infrared radiation on an unstructured tetrahedral mesh. It uses a traditional Sn source iteration technique for solving the first-order form for the transport equation. It has been applied to reactor and oil-well-logging problems with very complicated geometries. ATILLA has been commercialized via collaboration between CCS-4 and the ICEM-CFD Corporation.

DANTE

DANTE performs thermal radiation transport calculations in the x-ray regime on unstructured meshes in two dimensions and three dimensions. The solutions are highly nonlinear because of temperature-dependent opacities. This package can be coupled to ALE (Arbitrary Lagrangian Eulerian) hydrodynamics. The even-parity second-order form of the tranport equation is solved using a spherical-harmonic (Pn) angular approximation. CCS-4 personnel have been the leaders in developing the theory for this approach. It enables the transport equation to be solved via the solution of a sequence of sparse SPD (diffusion-like) linear systems. Researchers throughout the world are looking for efficient parallel methods for solving such systems. This effort will be able to use their results directly. DANTE was originally a research code with several transport options for both neutrons and photons.