What's really cool is that the simulations come up with the distribution of dark matter forming these bubble like voids with the walls being where the density is highest. I can't access the paper but here's an image of the voids and walls from the synopsis.
What's amazing is that these simulations show a distribution of dark matter that is similar to what is observed for the distribution of galaxies in our universe. Years ago sky surveys showed that the distributions of galaxies also show these voids and walls. Since dark matter constitutes about 25% of the mass-energy of the universe in the lamba-CDM models (Cold Dark Matter) and visible matter about 5% it makes sense that the visible matter would cluster along with the dark matter. The image below is from the Sloan Digital Sky Survey that shows the distribution of over 10,00 galaxies in a region of the sky. More information about the photo is given here. Notice the walls and voids in the distribution of galaxies. Pretty cool!!