Dynamics of Clusters of Galaxies

The abundance and internal characteristics of rich clusters of galaxies can provide useful constraints on models of large–scale structure formation. This article will review some recent three dimensional, multi–fluid simulations of cluster dynamics and discuss their impact on issues raised from optical and X-ray observations of clusters. In `bottom–up’ formation scenarios (such as the ubiquitous cold dark matter model), galaxies form before rich clusters; hence, cluster formation is intimately linked to galaxy formation which, in turn, is tied to star formation. I will examine two issues which appear relatively insensitive to galaxy/star formation — the baryon fraction in clusters and the connection between X–ray morphology and ${\mathrm{\Omega }}_o$ — and end with a topic that is intimately linked to it — dynamical biases in the cluster galaxy population.