Gas stripping and mixing in galaxy clusters: A numerical comparison
  study
  The ambient hot intra-halo gas in clusters of galaxies is constantly fed and
stirred by in-falling galaxies, a process that can be studied in detail with
cosmological hydro- dynamical simulations. However, different numerical methods
yield discrepant predic- tions for crucial hydrodynamical processes, leading
for example to different entropy profiles in clusters of galaxies. In
particular, the widely used Lagrangian smoothed particle hydrodynamics (SPH)
scheme is suspected to strongly damp fluid instabili- ties and turbulence,
which are both crucial to establish the thermodynamic structure of clusters. In
this study, we test to which extent our recently developed Voronoi particle
hydrodynamics (VPH) scheme yields different results for the stripping of gas
out of infalling galaxies, and for the bulk gas properties of cluster. We
consider both the evolution of isolated galaxy models that are exposed to a
stream of intra cluster medium or are dropped into cluster models, as well as
non-radiative cosmological sim- ulations of cluster formation. We also compare
our particle-based method with results obtained with a fundamentally different
discretisation approach as implemented in the moving-mesh code AREPO. We find
that VPH leads to noticeably faster stripping of gas out of galaxies than SPH,
in better agreement with the mesh-code than with SPH. We show that despite the
fact that VPH in its present form is not as accurate as the moving mesh code in
our investigated cases, its improved accuracy of gradient estimates makes VPH
an attractive alternative to SPH.
