Application and preservation are major themes in these activities which respond to warfighter requirements for survivable systems and effective nuclear weapons. Preservation, because the Defense Department’s understanding of nuclear weapon effects is based in large part on test data that is unique and, in many instances, perishable. Applications involve the packaging of U.S. nuclear data and physics understanding into advanced computational products that enable fundamentally new capabilities for warfighter interaction and visualization. In addition, there are aspects of our understanding of nuclear matters that require utilization of advanced computational resources, e.g., for investigation of the physics involved in weapon-target interactions, and for extrapolating from test results in circumstances in which new tests are not possible.
3.8.2 Scientific And Operational Computing Overview
3.8.2.1 Goals and Timeframes. By FY96, distribute computational aid providing an integrated methodology for calculating all nuclear weapon effects and Transient Radiation Effects on Electronics (TREE) Handbook. By FY97, provide users with on-line access to information and services at DASIAC (DoD repository for nuclear effects information). Complete bomb-in-structure modeling. Complete colleteral effects cloud transport model. By FY98, complete distribution of EM-1, primary engineering handbook for nuclear weapons effects; and transition computational support to a combination of the DoD High Performance Computing architecture and departmental hardware. Complete electro-thermal chemical gun model. By FY99, complete incorporation of underground nuclear test data into DARE (Data Archival and Retrieval Enhancement) system. By FY00, complete entry of nuclear simulator data into the DARE system. By FY01, complete incorporation of nuclear testing data and provide users with on-line access to DARE resources.
3.8.2.2 Major Technical Challenges. The nuclear effects computations program develops tools for accurate prediction of the evolution of turbulent fields embedded in explosions. Past work emphasized nuclear effects topics. Current focuses, which give particular emphasis to counterproliferation-relevant research, include turbulent combustion and afterburning induced by explosions in chamber systems (needed for engineering control over chemical explosions), formation of hazardous combustion clouds (to minimize collateral hazards associated with such events), turbulent combustion in guns (to produce range enhancement via controlled energy release), and turbulent mixing in bomb implosions (a topic to be addressed in stockpile revalidation, e.g., the DOE Advanced Scientific Computing Initiative). All of these applications are in line with direction from OSD to make use of nuclear technical expertise in designated non-nuclear applications.
It is generally recognized that turbulent mixing is the central unresolved physics problem for virtually all fluid-dynamic phenomena associated with explosions. A six-step approach has been demonstrated as providing reliable prediction of the evolution of turbulent explosion fields. This involves (1) convective mixing simulations of 3-D turbulent fields, (2) use of Adaptive Mesh Refinement to capture enough of the turbulence spectrum to reach the inertial range; (3) sub-grid modeling of molecular processes; (4) averaging of 3-D solutions to extract fields for engineering analysis; (5) corroboration of convective mix approximations by performing 3-D Navier-Stokes calculations of turbulent flows for limited spatial domains; (6) verification of numerical results by comparison with well-controlled laboratory experiments. A variety of state-of-the-art computational methods are used for the compressible and incompressible flow cases.
The nuclear testing database is unique and irreplaceable. Critical information is on perishable media, e.g., films and photography from the 1950s atmospheric test series. Data quality assurance is imperative. This is the last opportunity to involve experimenters who were participants in the atmospheric and underground nuclear test programs in the review of this data; their insights concerning the merits and limitations of this database must be captured and preserved. For computational aid products, user groups are employed throughout the development process to ensure products respond to customer requirements.
3.8.2.3 Related Federal and Private Sector Efforts. The Department of Energy organizations responsible for science-based stockpile stewardship plan to use the DOE Accelerated Strategic Computing Initiative as a primary mechanism for sustaining nuclear competence. Appropriate levels of DoD customer involvement, e.g., in dual-revalidation, are required.
3.8.3 Scientific and Operational Computing S&T Investment Strategy
3.8.3.1. Technology Development. All of the activities in this subarea involve technology development; there are no basic research or ATD/ACTD technology demonstrations.
DASIAC/DARE: DASIAC is the DoD Nuclear Information Analysis Center, chartered to preserve DoD nuclear-weapons-related information. DARE (Data Archival & Retrieval Enhancement) is a new program that uses optical media for long-term data preservation.
Computational Aids: This program develops the authoritative products used throughout the U.S. Government and allied nations for nuclear effects data and calculations, including EM-1, the primary technical reference for nuclear weapons effects, and a variety of engineering-oriented computational products.
Nuclear Effects Computations: This program provides computational
support for nuclear analyses and operations; an example of the
latter was direct technical support to the theater for hazard
forecasting during the Gulf War.