A Fluid Model for the Evolution of Large-Scale Structure

A numerical fluid model for the evolution of density fluctuations into the nonlinear regime in an expanding world model is developed, and the results are shown to be in a good agreement with analytic tests and an N-body model run. Two applications are presented. The first is a study of the behavior of mass sheets that might be compared to the "frothy", sheetlike distribution of galaxies seen in some parts of space. The second application is to the large-scale clustering of galaxies around Abell clusters. It is shown that the mass autocorrelation function and the cross-correlation of the mass density with the positions of peaks of the density can be adjusted to agree reasonably well with the galaxy-galaxy and cluster-galaxy correlation functions. However, the abundance of mass peaks is then low by a factor of ≡10 relative to the abundance of Abell clusters.