WCI scientists use a variety of support libraries and databases in their simulations. These libraries provide basic physics information for nuclear reactions, equations of state, material strengths, and opacities, etc., that is used by the integrated computer codes. Scientists at other national laboratories also make use of some of these libraries in their research. Several of these libraries are described below:
Equations of State
The Livermore Equation of State (LEOS) Project provides EOS data, access software and tools for LLNL applications that require accurate global material-specific EOS data. This data is an essential component in hydrodynamic simulations. The image to the left is a surface plot of the internal energy for the Glow Discharge Polymer EOS.
Strength of Materials
MIDAS is an easy-to-use and comprehensive common source for material properties including both experimental data and models and their parameters. It is the central repository for material-strength-related data and models with the long-term goal to encompass other material properties. The MIDAS framework consists of the SQL database containing both experimental data and material properties and model parameters, and a constitutive material model source code implementation library. [More information about MIDAS]
Opacity Distribution System
WCI's Opacity Distribution System (ODS) provides opacity data to applications at LLNL, LANL, and SNL 24 hours a day, 7 days a week. ODS is used by applications running both interactively and in the batch system. The system is architected similar to a database with a frontend API that applications use to call the Opacity Backend. The Opacity Backend is where the opacity data is stored and where new tables are generated. Click on image for larger version of ODS conceptual diagram.
Numerical Algorithm Support Libraries
WCI's numerical algorithm support libraries include those developed by the Center for Applied Scientific Computing (CASC), which conducts world class, collaborative scientific research and development in mathematics, computer science, and data science on problems critical to national security. The Center's core competencies include high performance computing, computational physics, numerical mathematics, computer science, and data science. CASC develops new insight and understanding through increased simulation fidelity by integrating multi-physics and multi-scale models, increasing resolution through advanced numerical methods or more efficient algorithms, and through the quantification of uncertainty.
The hypre library of high performance preconditioners features scalable multigrid methods for solving large, sparse linear systems of equations on massively parallel computers. The library provides solvers for both structured and unstructured grids through a unique set of linear system interfaces. The problems of interest arise in simulation codes in WCI as well as the broader DOE and world to study a variety of physical phenomena. [Go to HYPRE downloads]
SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) is an object-oriented C++ software library that enables exploration of numerical, algorithmic, parallel computing, and software issues associated with applying structured adaptive mesh refinement (SAMR) technology in large-scale parallel application development. SAMRAI provides software tools for developing SAMR applications that involve coupled physics models, sophisticated numerical solution methods, and which require high-performance parallel computing hardware. SAMRAI enables integration of SAMR technology into existing codes and simplifies the exploration of SAMR methods in new application domains. Due to judicious application of object-oriented design, SAMRAI capabilities are readily enhanced and extended to meet specific problem requirements. [More about SAMRAI]
The image to the left shows an example ALE-AMR multi-material calculation. The boxes with black borders represent the finest grid patches on the moving, deforming ALE mesh. Click on image for alarger version.
A mesh and field I/O library and scientific database
Silo is a library for reading and writing a wide variety of scientific data to binary, disk files. The files Silo produces and the data within them can be easily shared and exchanged between wholly independently developed applications running on disparate computing platforms. Consequently, Silo facilitates the development of general purpose tools for processing scientific data. One of the more popular tools that process Silo data files is the VisIt visualization tool.