  We report the results of 1-D hydrodynamical modelling of the evolution of gas
in galaxy clusters. We have incorporated many of the effects missing from
earlier 1-D treatments: improved modelling of the dark matter and galaxy
distributions, cosmologically realistic evolution of the cluster potential, and
the effects of a multiphase cooling flow. The model utilises a fairly standard
1-D Lagrangian hydrodynamical code to calculate the evolution of the
intracluster gas. This is coupled to a theoretical model for the growth of dark
matter density perturbations. The main advantages of this treatment over 3-D
codes are (1) improved spatial resolution within the cooling flow region, (2)
much faster execution time, allowing a fuller exploration of parameter space,
and (3) the inclusion of additional physics.
  In the present paper, we explore the development of infall models -- in which
gas relaxes into a deepening potential well -- covering a wide range of cluster
mass scales. We find that such simple models reproduce many of the global
properties of observed clusters. Very strong cooling flows develop in these 1-D
cluster models. In practice, disruption by major mergers probably reduces the
cooling rate in most clusters. The models overpredict the gas fraction in low
mass systems, indicating the need for additional physical processes, such as
preheating or galaxy winds, which become important on small mass scales.

Astrophysics