**The Terascale Simulation Tools and Technology Center**

PIs: J. Glimm^1,2^, D. Brown^3^, L. Freitag^3^, Co-PIs: E. D'Azevedo^5^,
P. Fischer^6^, P. Knupp^4^, X.L. Li^2^, M. Shephard^7^, H. Trease^8^
Affiliated Researchers: J. Drake^5^ (Climate), K. Ko^9^ (Accelerators),
S. Jardin^10^ (CEMM), C. Tzanos^6^ (Combustion), T. Mezzacappa^5^ (TSI),
T. Munson^6^ (TOPS), R. Armstrong^4^ (CCA)

**^1^Brookhaven National Laboratory, ^2^State University of New York at
Stony Brook,** **^3^Lawrence Livermore National Laboratory,**
**^4^Sandia National Laboratories, ^5^Oak Ridge National Laboratory,
^6^Argonne National Laboratory,** **^7^Rensselaer** **Polytechnic
Institute, ^8^Pacific Northwest National Laboratory , ^9^Stanford Linear
Accelerator** **Center, ^10^Princeton Plasma Physics Laboratory.**

The TSTT Center aims to eliminate the barriers associated with using
sophisticated meshing and discretization tools in DOE scientific
applications that involve complex geometry. To accomplish this goal we
are working directly with a number of SciDAC application partners to
insert TSTT technology directly into their codes. We are also creating
new technology to ease the development of powerful hybrid solution
strategies that employ multiple meshing and discretization techniques in
an interoperable and interchangeable way.

**The TSTT** **Vision.** Terascale computing environments provide an
unprecedented opportunity to perform numerical simulations at levels of
detail and accuracy previously unattainable. The Terascale Simulation
Tools and Technology (TSTT) center aims to help application scientists
exploit this opportunity by allowing them to more easily use high-order,
adaptive, parallel mesh and discretization tools. By working directly
with a number of SciDAC application teams to introduce these
technologies into their application domains, TSTT is making a near term
impact on the SciDAC applications, ensuring that new TSTT technology
will remain relevant to a broad range of DOE science applications. In
addition, by developing new technologies, we will eliminate the
technical and human barriers preventing the effective use of powerful
meshing and discretization techniques in large-scale scientific
simulations. A key goal of these efforts is to enable existing
techniques to be used in an interoperable and interchangeable way, thus
laying the groundwork for the development of new application codes that
employ powerful hybrid solution techniques.

**TSTT and SciDAC Applications.** We have invested a significant portion
of our resources in meeting with scientists from each of the SciDAC
application areas, analyzing their needs for advanced meshing and
discretization technologies, and working with them to demonstrate the
promise of such techniques in their application domains.

*Accelerator Design:* TSTT is helping to improve the computational
efficiency of electromagnetic simulation codes by inserting adaptive
technologies into an existing frequency domain code. (See Figure). This
has enabled highly accurate solutions using only a fraction of the
comparable fine resolution mesh. TSTT mesh generation technology is
being used to shorten the time required to generate high quality meshes
for complex accelerator geometries.

*Climate:* TSTT has investigated mesh generation strategies that create
high-quality meshes with mesh points focused over regions of high
altitude. TSTT and the members of the climate modeling community have
jointly developed a new preconditioner for spectral element simulations,
accelerating the solution of an important test problem for climate
scientists.

*Diesel spray formation:* TSTT is applying advanced front-tracking
technology to create a simulation code modeling spray formation in
diesel engine injection systems.

![](media/image1.pct)

*Fusion:* TSTT is investigating the use of high-order spectral elements
and adaptive finite element methods to improve the accuracy of MHD
fusion simulations.

*Computational Biology:* TSTT is applying meshing and solver technology
to develop a virtual microbial cell simulator.

**TSTT Technology Developments.** The TSTT center is working on new
technology developments in three primary areas.

1)  We are defining a common software interface for mesh and geometry
    access that all support. This allows application scientists and tool
    developers to use any compliant TSTT technology in a consistent,
    uniform way.

2)  We are demonstrating interoperability through one-on-one tool
    interfaces. The most notable of these efforts is the combination of
    front-tracking techniques with adaptive refinement techniques to
    create a new, highly accurate and computationally efficient
    technique for modeling sharp interfaces.

3)  We are developing new solvers and technologies to demonstrate or
    enable hybrid solution processes in SciDAC application areas. For
    example, we are creating a stand-alone mesh quality improvement
    toolkit and a discretization library that will work with all TSTT
    mesh management software packages through the TSTT interface.

    **Future Work.** The TSTT team will continue to work closely with
    all our SciDAC application partners to ensure that advanced meshing
    and discretization strategies can be used to their fullest extent.
    We will continue to develop common interfaces for TSTT meshing and
    discretization technology and demonstrate the utility of a software
    environment that supports interoperability for hybrid solution
    strategies.

    **The TSTT Team.** The TSTT partners, representing six DOE national
    laboratories (ANL, BNL, LLNL, ORNL, PNL, SNL) and two universities
    (RPI and SUNY SB), bring extensive expertise in structured,
    unstructured, and hybrid meshing and discretization technologies
    into one Center with the goal of delivering advanced, mesh-based
    simulation capabilities to scientific applications.

    **Benefits from Teaming.** The SciDAC team approach has transformed
    the manner in which the Center members conduct science by increasing
    the emphasis placed on collaboration, end use relevance, and
    integration. New technology based on interface development effort
    and interoperability of tools would not be possible without SciDAC
    support.

    **Further Information:**
    *[http://tstt-scidac.org](http://www.tstt-scidac.org/)*

    **Contact Information:**

    James Glimm, Brookhaven National Laboratory

    Phone: 631-333-8155, <glimm@bnl.gov>

    David L. Brown, Lawrence Livermore Nat. Lab.

    Phone: 925-424-3557, [dlb@llnl.gov](mailto:dbl@llnl.gov)

    Lori Freitag Diachin, Lawrence Livermore Nat. Lab.

    Phone: 925-422-7130, <diachin2@llnl.gov>