The Challenge of Modelling Galactic Disks
  Detailed models of galactic disk formation and evolution require knowledge about the initial conditions under which disk galaxies form, the boundary conditions that affect their secular evolution and the micro-physical processes that drive the multi-phase interstellar medium and regulate the star formation history. Unfortunately, up to now, most of these ingredients are still poorly understood. The challenge therefore is to, despite this caveat, construct realistic models of galactic disks with predictive power. This short review will summarize some problems related to numerical simulations of galactic disk formation and evolution. 
Andreas Burkert (University of Munich)