For context, this project just published a paper in Nature on this simulation [0] and a preprint is available [1]. One of the reasons this simulation is big news is its use of a new numerical technique (a "moving mesh"[2]) for the hydrodynamics which purportedly handles fluid instabilities with much greater accuracy. One effect of this is that cold gas flowing onto galaxies interacts with the hot gas halo around galaxies, which prevents that cold gas from going directly to the centers of galaxies. This results in larger simulated galaxies, which match better with observations.<p>[0] <a href="http://www.nature.com/nature/journal/v509/n7499/full/nature13316.html" rel="nofollow">http://www.nature.com/nature/journal/v509/n7499/full/nature1...</a><p>[1] <a href="http://arxiv.org/abs/1405.1418" rel="nofollow">http://arxiv.org/abs/1405.1418</a><p>[2] Previous work used either a fixed mesh with adaptive refinement for higher-resolution or a "smoothed particle hydrodynamics" scheme where particles are used to simulate fluid flows. Both schemes have advantages and disadvantages, but the claim is that this moving mesh code ("Arepo") does the best job of treating fluid instabilities. The paper describing the new code is at: <a href="http://dx.doi.org/10.1111/j.1365-2966.2009.15715.x" rel="nofollow">http://dx.doi.org/10.1111/j.1365-2966.2009.15715.x</a>