World Wide Metacomputing
M. Mueller
High Performance Computing Center Stuttgart

S. Sanielevici
Pittsburgh Supercomputing Center

A. Breckenridge
Sandia National Laboratory

S. Sekiguchi
Electrotechnical Laboratory, Japan

J. Brooke
Manchester Computing Centre

F-P. Lin
National Center for High-Performance Computing, Taiwan

T. Imamura
Japanese Atomic Energy Research Institute, Japan

Description:

 

URANUS:

The CFD-code URANUS (Upwind Algorithm for Nonequilibrium Flows of the University of Stuttgart) has been developed to simulate the reentry phase of a reusable space vehicle in a wide altitude velocity range. Simulation is the only way to get an idea what exactly happens during the reentry phase of a space vehicle, because measuring is very limited and expensive. Due to the role of chemistry and chemical reactions near the hot surface of the space vehicle, even wind tunnel experiments are not comparable to the flows and reactions appearing during a real reentry.

uranus1.gif (201461 bytes)
This picture shows the results of a CFD simulation of the re-entry of the X-38 crew rescue vehicle into the earths atmosphere

 

cluster.gif (53591 bytes)

P3T-DSMC:

This is a Direct Simulation Monte Carlo Simulation that was developed to simulate granular matter. Granular materials are ubiquitous in nature, industrial processing and everyday life. Examples range from small-scale particles in dust, cement or flour over medium-sized plastic granulates to the planetary rings on the astrophysical scale. Similarly broad are the physical phenomena controlling their behavior in transport, storage and processing.

However, despite their importance, continuum or other large-scale modeling still shows severe deficiencies and he understanding of the mesoscopic physics in these systems, as exemplified by fragmentation, dissipative effects, pattern formation, etc. is incomplete since many theoretical methods otherwise applicable to many-particle systems do not apply.

Often, large-scale computation is the only way to deepen our insight. The reason is that typical granular systems consist of million of particles and most phenomena are only visible after long time scales.
This picture shows a granular system of 100.000 dissipative particles demonstrating the clustering instability. The cluster size is already close to the system size. For a detailed study of the cluster growth dynamics large systems are therefore necessary.  Color indicates kinetic energy (blue=low, red=high)

ELECTRONIC STRUCTURE SIMULATION
First-principles electronic structure simulation of magnetic alloys, using an order-N algorithm. Running on 1480 T3E-1200 processors, this code was the first to sustain over 1 teraflop and won the 1998 Gordon Bell Prize. See http://www.psc.edu/science/wang.html for details."

JODRELL BANK RADIO-TELESCOPE DE-DISPERSION CODE
The search for fast (milli-second) pulsars has important implications for our knowledge of the large scale structure of our galaxy and for fundamental physics. However the pulsar signal is often below the level of background noise in the signal of the radio-telescope. Specialist hardware used to be deployed to enhance the pulsar signal above this background, but this can now be done more effectively using fast fourier transforms on a supercomputer. We intend to show two applications, both very demanding in terms of network bandwidth.

1. A search of data previously gathered from the radio-telescope using the metacomputer to correct for the effects of signal dispersion by the interstellar medium.

2. Using a known dispersion measure, to perform real-time processing of the signal from the telescope.

The challenge is to adjust the signal processing algorithms to the differing data transfer rates across the networks.

The computing challenge is to ensure that the processing algorithms maintain the balance between processing speed and network bandwidth.

RISK MANAGEMENT SYSTEM FOR ENVIRONMENTAL CRISIS
In the demonstration, there will be a simulation of source term estimation for the accident of Cesium contamination in Spain (Algeciras, 1998), using real observed data taken from monitoring devices in European countries, through a real-time visualization.

In general, when an accidental release of harmful pollutants into the atmosphere happens, it is requested to urgently estimate release conditions, e.g., emission point, period and amount (hereinafter source parameters), and to predict the environmental impacts as quick as possible. Thus quick respondence, i.e. the realization of real-time, is demanded of the simulation code. The estimation procedure consists of an atmospheric dispersion simulation for the possible source parameters and a statistical analysis to find the release condition providing the best fitted prediction. Since the atmospheric simulation part follows a large number of trial and error calculations, it also needs much computational resources which are not available at a single site. Therefore, it is very significant to develop a communication-intensive system using supercomputer resources all over the world as much as possible, which are connected through high bandwidth networks.