A New Model For Including Galactic Winds in Simulations of Galaxy
  Formation I: Introducing the Physically Evolved Winds (PhEW) Model
  The propagation and evolution of cold galactic winds in galactic haloes is
crucial to galaxy formation models. However, modelling of this process in
hydrodynamic simulations of galaxy formation is over-simplified owing to a lack
of numerical resolution and often neglects critical physical processes such as
hydrodynamic instabilities and thermal conduction. We propose an analytic
model, Physically Evolved Winds (PhEW), that calculates the evolution of
individual clouds moving supersonically through a uniform ambient medium. Our
model reproduces predictions from very high resolution cloud-crushing
simulations that include isotropic thermal conduction over a wide range of
physical conditions. We discuss the implementation of this model into
cosmological hydrodynamic simulations of galaxy formation as a sub-grid
prescription to model galactic winds more robustly both physically and
numerically.
