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September 12, 2013

Ice-Repellant Materials One Step Closer

Tiffany Trader

Scientists at GE Global Research are using the multi-petaflop Titan supercomputer at Oak Ridge National Laboratory to study the way that ice forms as water droplets come in contact with cold surfaces. They are working to develop “icephobic” materials that prevent ice formation and accumulation.

“We have observed that certain types of surfaces hinder ice formation, but the exact mechanism was unknown,” writes GE High Performance Computing Advocate Rick Arthur in a recent blog entry. “We use simulations as a means to gain insight into the conditions under which ice can be suppressed.”

There are numerous industrial systems that would benefit from such a technology. Wind turbines, offshore oil & gas drilling and production rigs can withstand very cold climates, even rain and snow, but ice can be a game-stopper. The researchers were awarded 80 million CPU hours on Titan through the Department of Energy ASCR Leadership Computing Challenge to advance this science.

The blog entry highlights the work of Dr. Masako Yamada, a scientist in GE’s Advanced Computing Lab. Simulations help Dr. Yamada and her colleagues to better understand ice resistance. The effectiveness of the candidate surfaces is evaluated based on four potential effects:

1) lowering freezing temperature, 2) delaying onset of freezing, 3) reducing adhesion (stickiness) between ice and surface, and/or 4) bouncing water droplets off before they can freeze.

Modeling and simulation are crucial to help narrow down potential candidates, but as Dr. Yamada explains, the computational technique – molecular dynamics – is notoriously time-consuming.

“‘Molecular’ means we track the position of every single water molecule. ‘Dynamics’ means we calculate very short slices of time,” she says.

Only the most powerful supercomputers in the world, machines like Titan, can handle this kind of compute-intensive work. Retooling their application to run on GPUs was another big step. The team achieved a 5x speedup by converting their code to run on Titan’s GPU accelerators.

“Even so,” says Yamada, “we can only model water droplets that are about 50 nanometers in size (far smaller than real world droplets) and we still cannot run our models to simulate as long a time period as we would like.”

The use of virtual models, as opposed to “real-life” experiments, allows for greater insight into the process:

“We can see exactly how the water molecules interact with the surfaces,” notes Yamada. “This is simply impossible using any physical test. In addition, in the virtual world, the results are not impacted by dirt, defects and other random sources of noise.”

Ultimately, the research will help establish a new class of materials. From safer aircraft engines to self-defrosting car windshields and even frustration-free ice cream scoops, the potential applications range as far as the imagination.

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