Galaxy as dissipative N -- body system. Chemical aspect
  The evolving galaxy is considered as a system of baryonic fragments embedded into the static dark nonbaryonic (DH) and baryonic (BH) halo and subjected to gravitational and viscous interactions. Though the chemical evolution of each fragment is treated in the frame of one -- zone model with instantaneous recycling, the local gas density and, therefore, its star formation (SF) activity is influenced by other interacting fragments. In spite of its simplicity the model provides a realistic description of the process of galaxy formation and evolution over the Hubble timescale. 
Peter Berczik and Sergei G. Kravchuk (Main Astronomical Observatory,   Kiev, Ukraine)