| SciDAC
The DOE Office of Science (SC) initiated
the Scientific Discovery through Advanced Computing (SciDAC)
program in 2001 to achieve three goals: (1) create a new generation
of scientific challenge codes
for terascale computers that can address the most critical scientific
problems in SC’s research programs; (2) create the mathematical
and computing systems software
to enable the scientific challenge codes to take full advantage
of the extraordinary capabilities of terascale computers; and
(3) create the collaboratory software infrastructure
to enable geographically separated scientists to effectively
work together as a team as well as provide electronic access
to both facilities and data.
In addition to computing resources,
NERSC is providing specialized consulting and algorithmic
support (see section below) for many SciDAC projects, including
several Integrated Software Infrastructure Centers (ISICs).
This section highlights some of the initial accomplishments
of these SciDAC projects as well as closely related research
by SciDAC investigators conducted on NERSC systems.
Applied Partial Differential Equations
The Applied Partial Differential Equations Center (APDEC)
is an ISIC that aims to develop a high-performance algorithmic
and software framework for solving partial differential equations
arising from problems in three important mission areas for
the DOE Office of Science: magnetic fusion, accelerator design,
and combustion. This framework will provide a new set of simulation
capabilities based on locally structured grid methods.
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| Figure
1 Volume-rendered image showing surface of maximum
heat release for the weak (a) and strong (b) turbulence
cases. |
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APDEC’s major accomplishment in 2002 was the first
fully resolved direct numerical simulation of turbulent methane
combustion with comprehensive chemistry and transport (19
reacting species, 84 reactions). These simulations allowed
researchers from Berkeley Lab’s Center for Computational
Sciences and Engineering (CCSE) to examine the basic structure
of the flame, including turbulent flame speed and flame surface
area, and to investigate the effect of turbulence-flame interaction
on the flame chemistry. The results indicate that flame wrinkling
is the dominant factor leading to the increased turbulent
flame speed (Figure 1). Future work will include a broader
range of turbulence scales, more detailed methane mechanisms,
and a range of configurations relevant to lean premixed combustion
experiments, such as turbulent jets and swirl burners.
INVESTIGATORS
P. Colella and J. Bell, Lawrence Berkeley National Laboratory;
D. Brown, Lawrence Livermore National Laboratory; M. Berger,
New York University; R. Leveque, University of Washington;
M. Minion, University of North Carolina; G. Puckett, University
of California, Davis; C. Rutland, University of Wisconsin.
PUBLICATION
J. B. Bell, M. S. Day, and J. F. Grcar, “Numerical simulation
of premixed turbulent methane combustion,” Proceedings
of the Combustion Institute (in press); Berkeley Lab report
LBNL-49331 (2002).
URL
http://davis.lbl.gov/APDEC/
DOE Science Grid
This SciDAC collaboration is working to define,
integrate, deploy, support, evaluate, refine, and develop
the persistent Grid services needed for a scalable, robust,
high-performance DOE Science Grid. It will create the underpinnings
of the software environment that the SciDAC applications need
to enable innovative approaches to scientific computing through
secure remote access to online facilities, distance collaboration,
shared petabyte datasets, and large-scale distributed computation.
In its first year, the project has focused on one of the
biggest problems in large-scale collaborations: a common authentication
and security approach that allows researchers from all over
the world to securely collaborate and share resources. The
DOE Science Grid and ESnet have developed a formal approach
to issuing and managing identity certificates in order to
support worldwide science collaborations. This process has
been put it into place for several DOE science collaborations,
including several international high energy physics collaborations
involving European Union Data Grid sites. As a result, high
energy physicists in the U.S. and Europe are now securely
collaborating and sharing science resources.
In a related issue, many scientific institutions use firewalls
to protect their internal networks and resources. The Science
Grid is developing procedures for establishing the trust that
is necessary to open up firewalls to Grid applications. These
procedures have been tested and accepted by the DOE Science
Grid sites (Lawrence Berkeley, Argonne, Oak Ridge, and Pacific
Northwest national laboratories and NERSC) and are being formalized
so that they may be used with other collaborating institutions.
Several applications are being prototyped on Science Grid
compute resources, including a regional air quality model
and a supernova cosmology data analysis application. Several
Grid R&D technology integration projects are also making
good progress, including the Python-wrapped Globus services
toolkit, which is being used to build some experimental Grid
system administration tools. A Grid Portal Developers Workshop
was held in Berkeley on June 4–5, 2002, allowing 24
developers from across the U.S. and Europe to share their
latest ideas and accomplishments.
INVESTIGATORS
W. E. Johnston, Lawrence Berkeley National Laboratory and
NASA Ames Research Center; R. A. Bair, Pacific Northwest National
Laboratory; I. T. Foster, Argonne National Laboratory; A.
Geist, Oak Ridge National Laboratory; W. T. C. Kramer, Lawrence
Berkeley National Laboratory/NERSC.
PUBLICATION
W. E. Johnston, “Using computing and data grids for
large-scale science and engineering,” Internatl. J.
High Perf. Computing Apps. 15, 223 (2001).
URL
http://doesciencegrid.org/
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