We are using cosmological numerical simulations to predict the expected physical properties of the Circumgalactic Medium (CGM) in the environment of masive starforming galaxies in the context of a ΛCDM cosmology. Our primary goal is to establish the gaseous flow pattern around the galaxies and the spatial extent to which winds impact on the CGM through comparison with the observations. Since we wish to compare with observations , as a first step in this pilot project we need to identify the sites of galaxies in the simulation. We do this by identifying their dark matter haloes. This is not straightforward, akin to identifying distinct clouds in the sky. An illustration of the complex regions in which galaxy haloes reside is shown in Figure 1. Different halo identification methods produce different halo catalogs, and different simulation numerical methods produce different haloes. We compare the haloes found using two different algorithms applied to results from two simulation methods to seek a range of halo masses for which the methods agree. Figure 2 shows agreement between these methods for haloes more massive than ten billion solar masses, corresponding to galaxy-size haloes. The flow fields around the haloes are currently being explored.