Troubled cosmic flows: turbulence, enstrophy and helicity from the
  assembly history of the intracluster medium
  Both simulations and observations have shown that turbulence is a pervasive
phenomenon in cosmic scenarios, yet it is particularly difficult to model
numerically due to its intrinsically multiscale character which demands high
resolutions. Additionally, turbulence is tightly connected to the dynamical
state and the formation history of galaxies and galaxy clusters, producing a
diverse phenomenlogy which requires large samples of such structures to attain
robust conclusions. In this work, we use an adaptive mesh refinement (AMR)
cosmological simulation to explore the generation and dissipation of turbulence
in galaxy clusters, in connection to its assembly history. We find that major
mergers, and more generally accretion of gas, is the main process driving
turbulence in the intracluster medium. We have especially focused on solenoidal
turbulence, which can be quantified through enstrophy. Our results seem to
confirm a scenario for its generation which involves baroclinicity and
compression at the external (accretion) and internal (merger) shocks, followed
by vortex stretching downstream of them. We have also looked at the infall of
mass to the cluster beyond its virial boundary, finding that gas follows
trajectories with some degree of helicity, as it has already developed some
vorticity in the external shocks.
