Turbulence modeling and the physics of the intra-cluster medium
  FEARLESS (Fluid mEchanics with Adaptively Refined Large Eddy SimulationS) is
a new numerical scheme arising from the combined use of subgrid scale (SGS)
model for turbulence at the unresolved length scales and adaptive mesh
refinement (AMR) for resolving the large scales. This tool is especially
suitable for the study of turbulent flows in strongly clumped media. In this
contribution, the main features of FEARLESS are briefly outlined. We then
summarize the main results of FEARLESS cosmological simulations of galaxy
cluster evolution. In clusters, the production of turbulence is closely
correlated with merger events; for minor mergers, we find that turbulent
dissipation affects the cluster energy budget only locally. The level of
entropy in the cluster core is enhanced in FEARLESS simulations, in accord with
a better modeling of the unresolved flow, and with its feedback on the resolved
mixing in the ICM.
