In the short time since it was introduced, UK researchers have documented a number of scientific advancements using the Cray XT4 system. Running a number of high resolution simulations at rapid speeds, the supercomputer has enabled researchers to gain a deeper understanding of important scientific phenomena in the fields of materials engineering, fluid dynamics and physics. These critical research projects include determining the composition of eggshell and how it's manufactured, the ease of turbulence creation using fractal grids, how ultra-fast lasers cut through targets without damaging tissue and the temperature of the Earth's core.

Simulating the temperature of the Earth's core. Professor Dario Alfè and colleagues from the University College in London first computed the temperature of the Earth's core in the late 1990s using the capacity of the supercomputers available at the time. The significantly advanced computing power of the HECToR Cray XT4 system has enabled Alfè to employ a more accurate method and reduce errors of his earlier calculation. The temperature of the Earth's core, which is molten iron under very high pressure, cannot be measured directly. Because of this, experiments have traditionally relied on recreating core conditions in the laboratory, an activity that is extremely complex and leads to highly variable experimental results. The HECToR results lend support to theoretical techniques and will help guide future experiments.

"This is something I'd wanted to do for a long time, but couldn't because there wasn't enough computing power. The Cray system is a fantastic machine - the best so far, making this experiment possible", stated Professor Alfè. The research team calculated the Earth's core at 6500 +/-400C.

Understanding the composition of eggshell and how it's manufactured. John Harding from Sheffield University used the HECToR system to simulate how protein and water molecules interact to form nanoscale-sized particles of calcium carbonate to create the structure of eggshell. Scientists believe that mechanisms by which chickens and other organic systems produce calcium carbonate - a component of rocks such as calcite and limestone - may be recreated to design new materials with useful properties. This project required many individual computer simulations, each involving hundreds of thousands of atoms, to understand how the molecules and particles interact.

"What we've come to understand is the how and the why - how proteins control the structure of calcium carbonate and why eggshell has the properties it does", stated John Harding. "We couldn't have undertaken a project of this size without HECToR and the Cray supercomputer."

Understanding how to create turbulence more efficiently using fractal grids. Chemical and food manufacturing industries use turbulence for mixing ingredients while some industries, like the aerospace and automotive industries, focus on reducing the negative effects of turbulence including noise and fuel consumption. Fractal grids have been shown to create turbulence with very little motion or energy and small changes to the grid have been shown to have an enormous effect on maximizing or reducing turbulence. Professor Christos Vassilicos of Imperial College in London conducted a number of simulations which allowed him to better understand the efficiency of fractal grids on turbulence production.

"There is no way I could have run these simulations before HECToR. I plan to conduct additional simulations to further shed light on how fractal grids impact turbulence and how industries can leverage this knowledge."

Understanding how ultra-fast lasers cut through cancer cells without damaging tissue. High-power, ultra-fast lasers are under development for many uses, including cancer treatment, because of their ability to cut through precision targets like cancer cells without damaging tissue. Professor Ken Taylor of Queen's University in Belfast used 8,000 cores of the HECToR Cray XT4 system to better understand their ability to do this. Professor Taylor employed fundamental physics to simulate the interaction of light at various wavelengths and intensities using helium, one of the smallest atoms.

"We've been able to build and solve a mathematical model of a real system using the Cray supercomputer. In future simulations, we will look at light of even shorter wavelengths including the x-ray range. Before HECToR, we couldn't go to shorter wavelengths or even simulate interactions at longer wavelengths for a wide range of light intensities. HECToR and Cray have allowed us to significantly advance the science in this field and I look forward to what we'll be able to achieve in the future."

"The HECToR Cray XT4 system has been in service less than a year and yet has already enabled users to tackle larger scientific problems than ever before with some great new results", stated Ulla Thiel, vice president of Cray Europe. "And the value-added Cray Centre of Excellence at HECToR at the University of Edinburgh along with the Computational Science and Engineering support provided by the Numerical Algorithms Group has made available the performance and application support that the UK academic community needs to tackle new areas of science and drive toward true capability computing. We are very encouraged by these early results and expect great things from the HECToR Cray XT4 in the future."

Researchers in the UK continue to use the Cray XT4 system in the HECToR program to further advance science in a variety of fields. Current experiments include the following:

• Dr. Richard Sandberg, University of Southampton, is pursuing numerical (compute-based) investigation of aircraft aerofoil noise. The project focuses on running large-scale simulations of turbulent flow over airfoils in order to detect additional noise sources other than trailing-edge noise. The data also is intended to help verify and improve noise prediction models. This work is very important, as noise generation at takeoff and landing is a major design consideration in modern aircraft.
• Professor Richard Catlow of the Materials Chemistry Consortium is working to improve the scalability of CASTEP, a software package used to calculate the properties of solids and surfaces. A new version of CASTEP developed for HECToR allows scaling to processor counts many times greater than was previously possible, using the Cray XT high performance interconnect. Professor Catlow's materials group will use this new technology to apply unprecedented amounts of computer power for this type of scientific problem.
• Dr. K. Stratford of the Soft Matter and Statistical Physics Group and Edinburgh Parallel Computing Centre at The University of Edinburgh is studying the properties of liquid crystals to understand how their structure can play an important role in determining their useful properties. Dr. Stratford is using up to 8,192 processors of HECToR's Cray XT4 system to run individual calculations, allowing the study of very large system sizes which are not subject to the errors that arise in small system sizes. It is hoped that this work will ultimately help improve the design of products such as liquid crystal displays.