  This paper is the second of the series of two papers, which focuses on the
derivation of an averaged 1D model for compressible bubbly flows. For this, we
start from a microscopic description of the interactions between a large but
finite number of small bubbles with a surrounding compressible fluid. This
microscopic model has been derived and analysed in the first paper. In the
present one, provided physical parameters scale according to the number of
bubbles, we prove that solutions to the microscopic model exist on a timespan
independent of the number of bubbles. Considering then that we have a large
number of bubbles, we propose a construction of the macroscopic variables and
derive the averaged system satisfied by these quantities. Our method is based
on a compactness approach in a strong-solution setting. In the last section, we
propose the derivation of the Williams-Boltzmann equation corresponding to our
setting.
