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__mp

I have access to the 6th fastest super computer and I'm pretty sure that it is not used to simulate nuclear explosions.

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What does it simulate?

Thanks.

Argonne National Labs, which is 5th fastest I think, is used for weather models, material science, and more[1]

[1]http://www.alcf.anl.gov/

There are dual-use systems which run classified and non-classified codes (they can be partitioned.. They typically live at LANL or LLNL rather than ANL or Berkeley (Berkeley in particlar doesn't do any classified work). Note that most classified codes are actually physics/material/explosion/plasma physics simulations and you can't always tell they are running on your system.

I checked the list of projects running on ALCF and I see some pretty obvious nuclear weapon stockpile stewardship and weapon design projects, such as "Validation Simulations of Macroscopic Burning-Plasma Dynamics"

Nucleosynthesis of heavier materials in supernova explosions and neutron star mergers are two cases of problems that I guess are used for "publicly" validating dark codes.

(I know a guy that Los Alamos is trying to recruit to do some dark work for them, and he does nucleosynthesis in neutron star mergers.)

Those would be useful, but typically the validation codes use terms like "multiscale combustion physics" or "coupled neutron/radiation transport".

I think the folks simulating supernova and neutron stars have a lot of physics overlaps, but I don't think that data is used directly for stockpile stewardship.

That should be Piz Daint at CSCS, so Super conductor behavior, weather and many other things.

Mostly non embarrassingly parallel problems, where its high speed interconnect pays off.

Can we please stop calling things "embarrassingly parallel". Just what the hell is embarrassing about highly parallelizable algorithms?

The term "embarrassingly parallel" doesn't refer to algorithms, it refers to problems which can be computed in such a manner, stating that they're not very interesting for parallel algorithms research. But yeah, it's kind of a stupid term. Would you be okay with "pleasingly parallel"? ;)

Potato, potato. I don't make the rules. I just think "embarrassingly parallel" sounds like a college freshman trying way too hard to sound smart and cool.

It called "embarrassingly parallel" because it is embarrassing for the Cray and other supercomputer vendors sales people when their expensive hardware does not outperform a 5 year old solution that cost 1/2 their fancy gear ;)

Otherwise data parallel is an other phrase that is used for the same concept.

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