models in Section \[sec:simcomparison\]. Finally, we summarize our main conclusions (§\[sec:conclusion\]).

Methodology
===========

The Simulations {#sec:boxes}
---------------

For the details of our simulations, we refer the reader to Cen (2012), although for completeness we reiterate the main points here. We perform cosmological simulations with the adaptive mesh refinement (AMR) Eulerian hydrodynamical code *Enzo* (Bryan 1999; O’Shea et al. 2004; Joung et al. 2009). We use cosmological parameters consistent with the WMAP7-normalized LCDM model (Komatsu et al. 2011): $\Omega_M$ = 0.28, $\Omega_b$ = 0.046, $\Omega_\Lambda$ = 0.72, $\sigma_8$ = 0.82, $H_o$ = 100 $h$ km s$^{-1}$ Mpc$^{-1}$ = 70 km s$^{-1}$ Mpc$^{-1}$, and $n$ = 0.96. We first ran a low resolution simulation with a periodic box of 120 $h^{-1}$ Mpc on a side, and identified a region centered on a cluster at $z = 0$. We then resimulated the region with high resolution, but embedded within the outer 120 $h^{-1}$ Mpc box to properly take into account large-scale tidal field effects and appropriate fluxes of matter, energy and momentum across the boundaries of the refined region.

The refined region we discuss in this paper is 21$\times$24$\times$20 $h^{-3}$ Mpc$^3$ centered on a cluster of $\sim$2$\times$10$^{14}$ M$_\odot$ with a virial radius (r$_{200}$) 