DAGH (which stands for Distributed Adaptive Grid Hierarchy)
was developed as a computational toolkit for the Binary
Black Hole NSF Grand Challenge Project. It provides the
framework to solve systems of partial differential
equations using adaptive finite difference methods. The
data structure that DAGH utilizes is the Hierarchical
Dynamic Distributed Array (HDDA). DAGH is used in several
- DAGH provides the computational infrastructure for the
binary black hole grand challenge, headed by Dr. Richard
Matzner at UT Austin with collaborators at eight other
institutions. The stated purpose of this project is to
develop a problem solving environment for the Nonlinear
Einstein equations describing General Relativity and to
provide controllable, convergent algorithms to compute
gravitational waveforms which arise from Black Hole encounters.
- DAGH is also the computational infrastructure for the
neutron star grand challenge. The goal for this project is
to use the important astrophysics problem of coalescing
binary neutron stars to drive the development of a multipurpose,
scalable, high-performance code, evolving both relativistic
gravitational fields and hydrodynamics, for relativistic
astrophysics and gravitational wave astronomy. Paul Saylor from
UIUC and other collaborators from NCSA, UIUC, Washington University,
and Max Planck Institute are involved in this project.
- DAGH has been integrated with IPARS (Integrated Parallel
Accurate Reservoir Simulator) to provide a problem solving
environment for parallel adaptive porous media and reservoir
simulations. This tool is developed to model the behavior of
fluids in permeable geologic formations such as petroleum and
natural gas reservoirs and ground water aquifers. The group is
headed by Dr. Mary Wheeler at the Center for Subsurface Modeling
at UT Austin.
- HDDA/DAGH is also used to design a multi-resolution data-
base for storing, accessing and operating on satellite
information at different levels of detail. This is a joint project
between Don Fussell and Harrick Vin from the Computer Sciences
Department, and Melba Crawford from the Center for Space Research
at UT Austin.
- Base HDDA objects have been extended with visualization,
analysis and interaction capabilities by J.C. Browne and
Manish Parashar at the Computer Sciences Department, UT Austin.
- DAGH is a part of a toolbox of computational components
which allow engineers to design and analyze composite materials
directly from the microstructural level. This will allow
engineers to use the toolbox as a replacement for a sizable
part of the laboratory experiments used in present design
practice. This project is headed by Gregory Rodin of the
Composite Material Group at UT Austin.
- Matt Choptuik and his students at UT Austin are investigating
the existence of boson stars, a likely cold dark matter candidate.
The physics of binary boson star coalescence and its implication
for astrophysics are being studied. An indirect application of this
project would be to use the boson star system as a simple model
problem to study the dynamics of compact objects. DAGH will
eventually be used to run the 3-dimensional numerical simulation code.
- Simulation of long range and high frequency wave propagation in
realistic earth models is an area of active research in geophysics.
Mrinal Sen from the Institute of Geophysics, Manish Parashar and
Jim Browne from the Department of Computer Sciences at UT Austin plan
to use DAGH to compute synthetic seismograms in laterally
heterogeneous anisotropic earth models. Parallelism and automated grid
refinements of DAGH are crucial to generating synthetic seismograms
for realistic earth models. They will be used in iterative modeling
of seismograms from earthquakes and man made explosions to infer the
properties of the earth's deep interior.
- To study the Laser-Plasma interaction David Fisher,
Scott Klasky, and Manish Parashar at UT Austin are using
DAGH as a part of their computational toolkit.
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