  We present results from recent simulations of the formation and evolution of
clusters of galaxies in a LambdaCDM cosmology. These simulations contain our
most physically complete input physics to date including radiative cooling,
star formation that transforms rapidly cooling material into aggregate star
particles and we also model the thermal feedback from resulting supernovae in
the star particles. We use an adaptive mesh refinement (AMR) Eulerian
hydrodynamics scheme to obtain very high spatial resolution (~ 2 kpc) in a
computational volume 256 Mpc on a side with mass resolution for dark matter and
star particles of ~ 10^8 M_solar. We examine in detail the appearance and
evolution of the core region of our simulated clusters.
