El Capitan, the fastest supercomputer in the world, can now simulate extreme events like shock waves or fluid mixing at high speed in a way that looks much closer to reality than ever before. The supercomputer was built for scientists at Lawrence Livermore National Laboratory (LLNL) in the U.S.
Usual computers are known for giving blurred pictures of these simulation events. El Capitan, however, creates high-resolution images, providing details about tiny features that can help analyze real physics.
The researchers used the supercomputer to simulate what happens to a tin surface when powerful shock waves and high-speed impacts hit it.
“The shocks were strong enough to melt the metal and throw a spray of hot liquified tin, known as ejecta, ahead of the surface,” said LLNL physicist Kyle Mackay.
“The simulation was noteworthy for its high fidelity, employing advanced physics models for mechanisms like surface tension, detailed equations-of-state, and especially its sub-micron mesh resolution,” he added.
When shock waves hit metal, it tends to melt and spray out tiny liquid droplets called ejecta. The simulations showed the effect of tiny scratches in the metal – details that don’t easily appear on other computer models.
This advancement is significant because such precise detail is essential for advancing real-world applications in physics, national defense, and fusion energy research.
Observing the Kelvin-Helmholtz instability
The researchers used LLNL’s multiphysics code MARBL to study the physical phenomenon called the Kelvin-Helmholtz instability – a phenomenon that occurs when two fluids of different densities rub against each other, similar to wind blowing over water and creating waves.
In extreme conditions like shockwaves or explosions, this effect becomes very turbulent and chaotic, making it hard to capture accurately in experiments.
The researchers developed a model in which a shockwave struck a minute ripple at the boundary between two materials, triggering intense mixing and forming vortex-like patterns.
These turbulent flows, resembling whirlpools, are notoriously complex and have long posed significant challenges for accurate modeling.
Exploring the results
El Capitan used 107 billion calculation points to track the physics. More than 8,000 AMD GPUs worked together to crunch the numbers.
The result was a time-lapse of fluid behavior under intense energy conditions, revealing intricate shear and shock patterns that mirror — and in some cases go beyond — what’s possible to observe in experiments.
“Experiments are the ultimate arbiter of physical truth, but can be difficult to extract necessary data from,” said Rob Rieben, a team researcher.
“High-fidelity simulations let us probe aspects of an experiment in a virtual manner that would not be possible to access in a real experiment. El Captain is a powerful scientific instrument for exploring physics via simulation at fidelities never seen before,” he continued.
Breaking the barriers
El Capitan enables researchers to run high-resolution simulations that capture complex physical processes directly, reducing dependence on simplified models and assumptions.
With 20 times more power than its predecessor, Sierra, El Capitan lets researchers run simulations far more often – about once an hour instead of once a day – and study details that are twenty times smaller.
El Capitan’s expanded capabilities will allow researchers to conduct more precise studies, accelerate testing, and generate insights that could benefit fields such as physics, defense, and energy research in the years ahead.